Large Whales With a Dorsal Fin
BLUE WHALE (B)[9]
Balaenoptera musculus (Linnaeus 1758)
[9] The letter in parentheses indicates whether the species is a baleen (B) or a toothed (T) whale.
Other Common Names
Sulphur-bottom.
Description
Blue whales are the largest living mammals. Though reports of maximum length and weight vary from one account to another, Antarctic blue whales are known to have reached lengths to 100 feet (30.5 m) and weights of over 150 tons (136,363 kg)[10] before stocks were severely depleted by whaling operations. North Atlantic blue whales may be expected to reach lengths of 80-85 feet (24.4-25.9 m). In all known populations of blue whales, females are slightly larger than males of the same age.
[10] The largest measured specimen was "just over" 100 feet (30.5 m); the largest specimen weighed, the 150-ton individual noted above, was 89 feet (27.1 m) long.
Viewed from above, the blue whale's rostrum is broad, flat, and nearly U-shaped (actually shaped like a Gothic arch, slightly flattened on the tip), with a single ridge extending from the raised area just in front of the blowholes towards but not quite reaching the tip of the snout.
The dorsal fin is extremely small [to only 13 inches (33 cm)] and variable in shape from nearly triangular to moderately falcate. In all cases, it is located so far back on the animal's tail stock that it is seldom visible until the animal is about to begin a dive.
Blue whales are light bluish gray overall, mottled with gray or grayish white. Some animals may have yellowish or mustard coloration, primarily on the belly, the result of the accumulation of diatoms during long stays in the cooler waters to the north. The undersides of the flippers are light grayish blue to white.
The baleen plates are all black.
Natural History Notes
The blow or "spout" is tall, to perhaps 30 feet (9.1 m), slender, vertical, and not bushy, as is the blow of humpback whales, for instance.
Although the blowing and diving patterns of blue whales may vary, depending on the speed of movement and the activity of the whale when it is encountered, they may be generally described as follows: If the animal is moving slowly, the blowhole and part of the head may still be visible when the dorsal fin breaks the surface, and the animal may settle quietly into the water without exposing the last portion of the tail stock or the tail flukes. If the animal is moving more quickly, however, or is about to begin a long dive, the blowhole disappears below the surface, a broad expanse of the back is exposed and disappears, and the dorsal fin emerges briefly just before the animal lifts its tail stock and flukes slightly above the surface before slipping out of sight.
In this species it can be generally stated that the maximum height of back in the area of the dorsal fin which is exposed above the surface as the animal sounds is approximately four times the height of the dorsal fin itself. The exposure of the tail flukes is unlike that of the humpback whale ([Fig. 39]), the right whale ([Fig. 50]), or the sperm whale ([Fig. 57]) in that when beginning a long dive all these other species raise the flukes high out of the water and usually descend at a steep angle. Blue whales lift the flukes only slightly, if at all.
Blue whales are relatively shallow feeders, feeding as they do almost exclusively on "krill" (small shrimplike crustaceans), most of which are distributed in the surface 330 feet (100 m). Blue whales usually occur singly or in pairs.
May Be Confused With
At sea, blue whales may be confused with fin whales (p. [26]) and though the two are sometimes difficult to distinguish from a distance, the following key differences permit identification at close range:
See also comparison of fin whale and sei whale (p. [26]).
Distribution
Though blue whales have been reported from the pack ice to Cristobal Harbor, Panama Canal Zone, their normal range in the western North Atlantic is more limited. In spring and summer months (about April through at least August) they can be expected in the northern portion of their range, at least as far north as the Arctic Circle, feeding on the krill abundant in those waters. A small portion of the population may venture north, beyond the Circle. In fall and winter the population moves south, presumably into temperate and perhaps to tropical waters. Reliable records include animals from observations off Long Island and Ocean City, Md.
Though southern limits of the species are poorly known, there are no records from Florida or the West Indies and no verified records from the Gulf of Mexico.
Summaries of blue whale distribution based on records when the species was more numerous indicate that they were found during spring and summer months in some abundance on the Nova Scotian Banks, the St. Lawrence Gulf and estuary, the Strait of Belle Isle, Grand Bank, and in the waters off the coasts of Iceland, southern Greenland, and the Davis Straits and Baffin Bay. (Some individuals have entered the Hudson Strait but not apparently Hudson Bay itself.)
Historically, a few animals apparently appeared off the coast of southeastern Canada as early as February. It was speculated that from there a portion of the population underwent a migration from the Strait of Belle Isle north through the Davis Straits to the waters off western Greenland. Some individuals entered the Gulf of St. Lawrence after the ice was clear and remained behind until as late as November. In the fall months, certainly by November, the northern portion of the population had begun retreating to the south in front of the advancing ice. The remainder apparently also underwent this migration as well, since blue whales have historically been nearly absent from Canadian waters during midwinter.
Many of the migrating individuals were assumed to continue south to temperate and, less frequently, to tropical water where they calved. It should be emphasized that though all of the southward and the subsequent northward migrations were presumed to be along pelagic routes, details were poorly documented.
Blue whales have been reported in both shallow inshore and deep oceanic zones.
Despite considerable attention in the popular literature to the plight of the blue whale populations and frequent statements that they are near extinction, blue whale stocks in the western North Atlantic appear more abundant than has been usually reported. While present stocks are far short of previous population sizes, which may have exceeded 200,000 individuals worldwide, they should be sufficiently large for the species to continue their increase, barring renewed exploitation.
Stranded Specimens
Stranded blue whales can be readily identified by 1) the large body size (to 85 feet [25.9 m]); 2) the broad flat head; 3) the all-black baleen plates (270-395 in number), which are usually barely more than twice as long as they are wide; and 4) the 55-88 ventral grooves extending to the navel or beyond ([Table 2]).
Depending on the state of decay and the position of the stranded specimen, any of the body characteristics described for living animals may also be used to positively identify the specimen.
Figure 9.—Closeup views of swimming blue whales off British Columbia ([top]) and Baja California ([bottom]). In both photos note the broad rounded appearance of the head and the single, prominent central head ridge. In the animal on the top note also the black baleen plates, barely visible at the front of the slightly open mouth. In the animal on the bottom note the pattern of light grayish-white mottling along the back and the raised areas around the blowholes. These features clearly mark these animals as blue whales. (Photos by R. M. Gilmore [top] and K. C. Balcomb [bottom].)
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Figure 10.—The dorsal fins of blue whales may vary from distinctly triangular ([top]) to broadly rounded ([middle] and [inset]) to smoothly falcate in appearance ([bottom]). Regardless of its shape, however, the fin is always located well back on the tail and does not become visible until long after the animal's blow. (Photos by Japanese Whales Research Institute, courtesy of H. Omura, mid-Pacific [top]; S. Leatherwood, southern California (middle and inset); and F. W. True, northern North Atlantic, courtesy of U.S. National Museum [bottom].)
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Figure 12.—A sequence showing fast-swimming blue whales off southern California. The animal rises rather steeply to the surface ([a]), emits a tall, vertical blow ([b], [c]), shows its broad bluish back, mottled with grayish white, and its small dorsal fin ([d], [e]), and then dives out of sight ([f]). When swimming in this manner, blue whales sometimes raise their tail flukes slightly above the surface before beginning their long dives ([g]). (Photos by J. F. Fish [a-f] and K. C. Balcomb [g].)
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Figure 13.—Two views of blue whales on the ramps of whaling stations in Japan ([top]) and at Hermitage Bay, Newfoundland ([bottom]). Note the broad rounded appearance of the head, the single central head ridge, and the dark bluish-gray coloration, interrupted only by mottlings of grayish white. In the animal on the bottom note the all-black baleen plates, which are very broad relative to their length. (Photos by Japanese Whales Research Institute, courtesy of H. Omura [top]; and F. W. True, courtesy of U.S. National Museum [bottom].)
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Figure 14.—Dead blue whales, harpooned and afloat off the stern of a factory ship in the Antarctic ([top]), and on the deck of a whaling station in western Canada ([bottom]). In both, note the numerous ventral grooves (from 55 to 85 or more) extending to the region of the navel and sometimes beyond, and the light coloration of the undersides of the flippers. Even though grooves are often present above the flippers, and occasionally even on the side of the head, counts of ventral grooves are usually made between the flippers. (Photos by Japanese Whales Research Institute, courtesy of H. Omura [top]; and G. C. Pike, courtesy of I. MacAskie [bottom].)
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FIN WHALE (B)
Balaenoptera physalus (Linnaeus 1758)
Other Common Names
Finback whale, finner, razorback, common rorqual.
Description
Fin whales have been reported to reach 79 feet (24 m). Females are slightly larger than males of the same age.
The back is distinctly ridged towards the tail, prompting the common name "razorback" whale.
The rostrum is narrower and more V-shaped than that of the blue whale and has the same sort of single distinctive head ridge. The top of the head is flat, though slightly less than that of the blue whale.
The dorsal fin is up to 24 inches (61 cm) tall; angled less than 40° on the forward margin, located slightly more than one-third forward from the tail, and appears on the surface shortly after the blow.
All individuals are dark gray to brownish black on the back and sides with none of the mottling present on blue whales and are rarely as heavily scarred as sei whales. Along the back, just behind the head, there is a grayish-white chevron, with the apex along the midline of the back and the arms of the chevron oriented posteriorly, which is sometimes distinctive and may be visible as the animals surface to breathe. The undersides, including the undersides of the flukes and flippers, are white. On the head, the dark coloration is markedly asymmetrical, reaching farther down on the left than on the right side. The right lower lip, including the mouth cavity, and the right front baleen (approximately one-fifth to one-third) are yellowish white. Occasionally the right upper lip is also white. The remainder of the plates on the right side and all those on the left side are striped with alternate bands of yellowish white and bluish gray. The fringes of the plates are brownish gray to grayish white.
Natural History Notes
Fin whales are one of the most common baleen whale species in the world and constitute a major portion of the whaling catch. They are reportedly one of the fastest of the big whales (sei whales may be slightly faster) possibly reaching burst speeds in excess of 20 knots, and were not an important commercial species until the comparatively recent development of fast catcher boats and the depletion of blue whale stocks.
A fin whale's blow can be from 15 to 20 feet (4.6 to 6.1 m) tall and has been described as an inverted cone or an elongated ellipse.
Fin whales dive to at least 755 feet (230.1 m). This depth is probably deeper than that of either blue or sei whales, a factor usually reflected in differences among the surfacing, blowing, and diving characteristics of these three species. When they are moving leisurely at the surface, fin whales expose the dorsal fin shortly after the appearance of the blowholes, slightly later than that of the sei whales. When they are surfacing from a deeper dive, however, they surface at a steeper angle, blow, submerge the blowholes, and then arch the back and dorsal fin high into the air before beginning another long dive. In this species it can be generally stated that the maximum amount of the back in the area of the dorsal fin which is exposed above the surface as the animal sounds is approximately 2 times the height of the dorsal fin. Fin whales do not show their tail flukes when beginning a dive.
Unlike blue or sei whales, fin whales do breach on occasion. When they do leap clear of the water, fin whales usually reenter with a resounding splash, like that made by humpback and right whales and not smoothly, head first, as minke whales often do.
Fin whales are sometimes found singly or in pairs but more often occur in pods of six or seven individuals and many pods consisting of as many as 50 animals may be concentrated in a small area.
Fin whales calve and breed in winter, mostly in temperate waters.
Atlantic fin whales eat a wide variety of foods, including krill, capelin, squid, herring, and lanternfish.
May Be Confused With
Fin whales may be confused with blue whales, sei whales, and, in the southernmost portion of their range, with Bryde's whales. They may be distinguished from the blue whales by differences in overall coloration, coloration and shape of the head, and the size, position, and time of appearance of the dorsal fin at the surface (see p. [19]). After close examination they may be distinguished from Bryde's whales by the presence of three ridges along the head (of the Bryde's whale) and by the smaller, more sharply pointed falcate dorsal fin of the Bryde's whale (see [Fig. 31]). They may be distinguished from sei whales in the following similar ways:
Distribution
Fin whales are probably the most numerous and widely distributed large whale species in the western North Atlantic.
Fin whales summer from below the latitude of Cape Cod, Mass., north to the Arctic Circle. (They are frequently seen between New York and Bermuda this time of year.) Within this zone they may sometimes be seen very close to shore and appear to be concentrated between shore and the 1,000-fathom curve from at least lat. 41°20' to 57°00' N. In recent years they have been reported in relatively large numbers in the Gulf of Maine from March through June, off Newfoundland as early as June but increasing to August, and entering Davis Straits and beyond in substantial numbers in midsummer to late summer. There is some evidence that the animals venturing farthest north are the largest individuals of the species. Movements of the population(s) southward have usually begun by October, though some fin whales sometimes remain in the northern seas sufficiently long to become trapped in the ice and killed.
During winter the range of fin whales spreads out from the advancing ice southward, reaching at least to the coast of Florida, into the Gulf of Mexico, and to the Greater Antilles, though fin whales are not at all common in tropical waters. During the winter many fin whales move into offshore waters. Northward migrations probably begin in midspring.
Fin whales may be found in Cape Cod waters all year long.
There may be two or possibly three separate stocks of fin whales in the western North Atlantic, one more northern cold-adapted stock and another more southern stock. The ranges of the two stocks appear to overlap, such that the winter range of the northern stock probably becomes the spring and summer range of the more southern stock. The third stock may consist of an isolated population in the northern Gulf of Mexico.
Stranded Specimens
Stranded fin whales may be most readily identified by 1) the yellowish-white coloration of the right front baleen and the right white lower lip; 2) the numerous baleen plates (262-473 in number); 3) the numerous ventral grooves (56-100 in number) extending to the navel and beyond ([Table 2]); and 4) the broad, flat sharply pointed head with only a single head ridge.
Figure 22.—In this partly flensed fin whale, at Blanford, Nova Scotia, note the white lower lip and the white baleen in the right front. [[See larger main image.]] The [inset photo] shows the right upper jaw of a fin whale with the baleen intact. (Photos by H. E. Winn, and from the North Pacific by Japanese Whales Research Institute, courtesy of H. Omura [inset].)
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SEI WHALE (B)
Balaenoptera borealis Lesson 1828
Other Common Names
Pollack whale, sardine whale, Rudolphi's rorqual.
Description
Sei (pronounced "say") whales have been reported to reach 62 feet (19 m).
The snout is less acutely pointed than that of the fin whale but when viewed from the side appears slightly arched. In general, the head is intermediate in shape between that of the blue whale and that of the fin whale. The dorsal fin, which is from 10 to 24 inches (25.4 to 61 cm) tall and strongly falcate in adult animals, is located about two-thirds of the way back on the back, farther forward than that of the blue or fin whales. Sei whales are dark steel gray on the back and sides, and on the posterior portion of the ventral surface. The body often has a galvanized appearance due to scars possibly resulting from lamprey bites inflicted during migrations into warmer waters. These scars may be dark gray to almost white in color. On the belly there is a region of grayish white that is confined to the area of the ventral grooves. Neither the flippers nor the tail flukes are white underneath. The right lower lip and the mouth cavity, unlike those of the fin whale, are uniformly gray. The baleen plates are uniformly grayish black with fine grayish-white fringes. (A small number of sei whales have been noted to have a few half-white plates near the front of the mouth, a feature which might result in their confusion with fin whales.)
Natural History Notes
The blow of sei whales is an inverted cone rarely taller than 15 feet (4.6 m).
Sei whales are generally skimmer feeders and do not usually dive very deeply. For that reason they usually surface at a shallower angle than fin whales. The head rarely emerges at a steep angle (except when the whales are chased). Instead, the blowholes and a major portion of the back, including the dorsal fin, become visible almost simultaneously and remain visible for relatively long periods of time. In this species it can be generally stated that the amount of the back in the area of the dorsal fin which is exposed above the surface as the animal sounds is approximately the same height as the dorsal fin. When they begin another dive, sei whales do not arch the tail stock or flukes high. Instead, they normally submerge by slipping quietly below the surface, often remaining in view only a few feet down and leaving a series of tracks or swirls on the surface as they move their tail flukes. When they are feeding in this manner, sei whales may exhibit a highly regular blowing and diving pattern over long periods of time.
Sei whales usually travel in groups of from two to five individuals, though they may concentrate in large numbers on the feeding grounds.
In the northern portion of their range, sei whales feed on copepods. Throughout the remainder of the range, however, their food is more varied and also includes krill and a variety of small schooling fishes. The species derived its common name, in fact, from its frequent occurrence with or near sei fish.
May Be Confused With
The sei whale's smaller size and decidedly taller, more falcate dorsal fin located well more than one-third forward from the tail should prevent confusion with the blue whale. At a distance, however, sei whales are difficult to distinguish from either fin whales or Bryde's whales. The primary clues for distinguishing them from fins are the differences in swimming, blowing, and diving characteristics tabularized in detail on p. [26] and the asymmetrical coloration of the fin whale.
Sei whales may be distinguished from Bryde's whales only upon close examination. The dorsal fin of Bryde's whales is small, to 18 inches (45.7 cm), sharply pointed, and often worn on the rear margin. If close examination is possible, the sei whale will be seen to have only a single head ridge. Bryde's whales have two additional ridges—one on each side of the main ridge. Bryde's whales are primarily fish feeders and their diving behavior more closely resembles that of a fin whale than that of a sei whale. (See p. [37]).
Distribution
The distribution and migrations of the sei whale during most of the year are rather poorly known. The species is known to avoid the colder regions near the pack ice and to range from Iceland south to the northeast Venezuelan coast and the northeast and southwest Gulf of Mexico. There are also records from Cuba and the Virgin Islands. Along the northeast United States and eastern Canadian coasts, where most research on sei whales has been conducted, the species migrates from New England through the Blanford, Nova Scotia area in June and July, is found in small numbers off eastern Newfoundland in August and September (abundant in Placentia Bay, Newfoundland in August), and continues northward to the Davis Straits in September and October. An offshore stock may be found year-round in the Labrador Sea. The summer range (May to September or October) extends from New England to southern Arctic waters. Though some individuals remain behind through November, the southward movement of the bulk of the population presumably begins in October. In general, sei whales do not venture as far north as fin whales but may have a greater tendency to enter tropical waters.
Stranded Specimens
Stranded sei whales are most likely to be confused with fin whales or Bryde's whales. The three head ridges of the Bryde's whale (sei whales have only one) assist in distinguishing sei whales from Bryde's whales. They may be distinguished from fin whales and all other rorquals by the following characteristics: 1) The color of the baleen plates—uniformly ash black with a blue tinge and fine white bristles ([Table 2]). 2) The density of bristles on the plates—sei whales have from 35 to 60 baleen fringes per centimeter; all other rorquals have far fewer (less than 35). 3) The relative lengths of the ventral grooves—the grooves of sei whales end well before the navel; those of blue, fin, and Bryde's whales extend at least to the navel. 4) The relatively small numbers of ventral grooves (38-56)—both blue and fin whales have more; Bryde's whales have approximately the same number.
If the animal is not in an advanced state of decomposition, the region of white coloration of the belly may also be visible.
Figure 27.—A freshly dead sei whale from the Pacific ([top]) and a stranded specimen in an advanced stage of decomposition at Cape Island, S.C. ([bottom] and [inset]). Note that even though the distinctive coloration of the fresh specimen has faded on the rotting specimen, the numbers and lengths of the ventral grooves (38 to 56 in number and stopping well short of the navel) still permit the specimen to be distinguished from fin, blue, and Bryde's whales, in all of which the grooves extend at least to the navel. (Photos by Japanese Whales Research Institute, courtesy of H. Omura [top]; and J. G. Mead [bottom and inset].)
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BRYDE'S WHALE (B)
Balaenoptera edeni Anderson 1879
Other Common Names
None known.
Description
Bryde's whales reach a maximum length of approximately 46 feet (14 m). They closely resemble sei whales in external appearance. At a distance, the head of this species is similar in profile and general appearance to that of the sei whale. The most distinctive field characteristic of the species, however, is the presence of three ridges along the head anterior to the blowhole. In addition to the medial ridge characteristic of all the other balaenopterid species, Bryde's whales have two secondary ridges on the top of the head—one along each side even with the blowhole running forward towards the tip of the snout. If they can be examined at close range, Bryde's whales can be positively identified by this character alone.
The dorsal fin of Bryde's whales is up to 18 inches (45.7 cm) tall, extremely falcate, pointed on the tip, located well more than one-third forward from the tail, and is often irregularly notched or frayed on the rear margin from unknown causes. Bryde's whales are dark gray overall, though some individuals, like some minke whales, have a small region of gray on each side just forward of the dorsal fin.
Natural History Notes
Bryde's whales, like minke whales, reportedly often approach close to vessels as if curious about them. During this time they may be examined carefully and their identifying characteristics seen.
Though euphausiids may be an important food for this species in limited areas, Bryde's whales often feed on schooling fish (including pilchards, anchovies, herring, and mackerel). This food preference is reflected in the diving behavior of the species. Bryde's whales are not "skimmer" feeders; they are deeper divers. When they surface to breathe, they often rise more steeply to the surface, exposing much of the head, roll the body sharply, and hump up the tail stock before beginning another dive. In this species, as in the fin whale, it can be generally stated that the amount of the back which is exposed above the surface as the animal sounds is approximately twice the height of the dorsal fin. They apparently do not raise the tail flukes when beginning a dive.
May Be Confused With
At sea Bryde's whales may be confused with sei whales, fin whales, and perhaps minke whales.
They may be most readily distinguished from sei whales by the characteristics discussed on p. [32] and by differences in diving behavior. The shallow-feeding sei whales surface and blow at regular intervals over long periods of time. Bryde's whales are deeper divers, less likely to surface, and blow at evenly spaced intervals. If they are seen only briefly or at a distance, however, the two species may be impossible to differentiate.
During the winter months, when fin whales may venture into tropical waters, they may also be confused with Bryde's whales. But fin whales seldom exhibit curiosity about boats. In addition, the dorsal fin of the fin whale is larger, is located farther back on the back than that of Bryde's whale, and does not become visible as soon after the blow. It is also less likely to be worn on the rear margin than that of a Bryde's whale.
The head of the fin whale is more acutely pointed. Furthermore, the right lower lip and the right front baleen of the fin whale are white. The baleen and the right lower lip of Bryde's whales are dark gray. If the animals can be approached closely from the right side, positive identification is possible using these differences in color.
Like Bryde's whales, minke whales often approach close to vessels. But minke whales have an acutely pointed snout, a single head ridge, and a white band on each flipper. Further, minke whales rarely reach 30 feet (9.1 m) in maximum length.
Distribution
The distribution of Bryde's whales is rather poorly known, no doubt in part, because the species is difficult to positively identify at sea, and records of its occurrence may have often been confused with those of sei whales, fin whales, or minke whales. From stranded animals and confirmed sightings at sea, the species appears to be found primarily near shore in areas of high productivity in tropical or subtropical waters, though it ventures into warmer temperate waters as well. It has been reported from Virginia south into the northeast Gulf of Mexico and the southeast Caribbean, and southern West Indies (Curacao and Granada). To date no migration has been described for the species.
Stranded Specimens
Stranded Bryde's whales can be positively identified by the three ridges along the top of the head from the area of the blowhole to the tip of the snout. All other species of balaenopterid whales, except humpback whales have but a single ridge. If the head of a stranded specimen is buried in sand, is decomposed beyond recognition, or is otherwise inaccessible for identification, Bryde's whales can still be distinguished from sei whales by differences in the relative lengths of the ventral grooves ([Table 2]) and from both the fin whale and the sei whale by differences in the characteristics of the baleen plates ([Table 2]).
Figure 31.—Bryde's whales in the Gulf of California and north of Hawaii (inset). In both, note the tall, sickle-shaped appearance of the dorsal fin, much like that of the sei whale. In the animal in the [larger photo] note the ragged rear margin of the dorsal fin, a frequently observed characteristic in Bryde's whales. In the animal [on the left] note also the region of gray on the sides in front of the dorsal fin. (Photos by W. C. Cummings and S. Ohsumi [inset].)
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Figure 32.—Stranded Bryde's whales at Walnut Point, Va. ([top]) and Panacea, Fla., Gulf of Mexico ([bottom]). In both animals note the head shape similar to that of the sei whale, and the three distinct head ridges. In the animal on the bottom, note that the two outermost ridges have their origin in grooves beside the blowholes. In the animal on the top, note also the baleen plates, up to at least 300 per side and dark gray with coarse gray bristles. There is infrequently a rather wide interval at the front of the mouth between the left and right rows of baleen. (Photos by U.S. National Museum, courtesy of J. G. Mead [top] and M. B. Rank, courtesy of Wide World Photos [bottom].)
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HUMPBACK WHALE (B)
Megaptera novaeangliae (Borowski 1781)
Other Common Names
Humpbacked whale, bunch, hump whale, or hunchbacked whale.
Description
Humpback whales reach a length of 53 feet (16.2 m).
The body is robust, narrowing rapidly on the tail stock. The head is quite broad and rounded, somewhat like that of the blue whale. The head ridge characteristic of other balaenopterid species is indistinct and is replaced in prominence by a string of fleshy "knobs" or protuberances, many more of which are randomly distributed on the top of the head and on the lower jaw. There is a distinctive rounded projection near the tip of the lower jaw. Humpback whales carry many barnacles and whale lice. The baleen plates are all black with black or olive-black bristles.
The flippers are very long (nearly a third as long as the body), are scalloped on at least the leading edge, and are nearly all white.
The dorsal fin, located slightly more than two-thirds of the way back on the back in approximately the same position as that of the fin whale, is small and varies in size and shape from a small, triangular nubbin to a more substantial, sharply falcate fin. The dorsal fin frequently includes a step or hump, which is quite distinct when the animal arches its back to begin a dive and from which the species derives its common name.
Humpback whales are basically black in color with a white region of varying size on the belly, which upon close examination may often be seen to be crosshatched with thin dark lines; the flippers and the undersides of the flukes also are white.
Natural History Notes
The blow of humpback whales is from 8 to 10 feet (2.4 to 3.1 m) tall and has been described as balloon-shaped. It is wide relative to its height. Feeding humpback whales habitually blow 4-8 times at intervals of 15-30 s after a long dive. In the tropics they habitually blow 2-4 times in succession when beginning a long dive. In diving, humpback whales throw the tail flukes high into the air, exposing the sometimes white undersurface and the rippled rear margin.
Humpback whales often leap clear of the water, raise a flipper, and slap it against the water, or "lobtail," raising the tail high into the air and bringing it crashing back to the water in a loud report. Often, particularly when they are encountered on their tropical breeding grounds, humpback whales will be found lying on their sides with a long flipper in the air.
Humpback whales feed on krill and schooling fish.
May Be Confused With
From a distance humpback whales may be confused with any of the other large balaenopterid (rorqual) whales—blue, fin, sei, or Bryde's. Although it is highly variable, the dorsal fin most closely resembles that of the blue whale. However, it is located farther forward on the back. Humpback whales distinguish themselves from the remainder of the rorquals by their habit of raising the flukes high into the air when starting a long dive. (In very shallow water they may not raise the flukes at all.) The only other rorqual to do so—the blue whale—raises the flukes slightly or not at all.
Under some conditions humpback whales may be confused with sperm whales at a distance. When arching the back to begin a dive, both may show a distinct hump. Both species frequently raise their flukes nearly vertically when beginning a long dive but differ in several ways. The flukes of humpback whales show varying amounts of white beneath, are pointed on the tips, and are distinctly concaved and irregularly rippled on the rear margin. Those of sperm whales are all dark and more flattened and even along the rear margin. Further the species can be distinguished in the following ways:
| Humpback Whale | Sperm Whale |
|---|---|
| BLOW | |
| Projects upwards from centerof head. Usually blows4-8 times (2-4 times intropics) before diving. | Projects obliquely forwardfrom left side of snout.Usually blows many times(20-50 or more) before diving. |
| HEAD | |
| Raised area around blowholes,knobs on upper surface. | Blunted, long, smooth. |
| FLUKES | |
| Often white underneath,concaved and scalloped onrear margin, deeply notched. | Smooth, all black on rearmargin. |
| FLIPPERS | |
| Extremely long (to one-thirdof body), white and scallopedon leading edge. | Short; all black. |
| DORSAL FIN (OR HUMP) | |
| Triangular to falcate fin,including a step or hump infront of the dorsal fin;smooth. | Rounded hump, two-thirdsback on back followed byknuckles or crenulations. |
When they can be examined at close range, humpback whales can be easily distinguished from all other large whale species with a dorsal fin by the tuberosities or knobs on the head, by the long white flippers scalloped on the leading edge, by the small distinctive dorsal fin, and by their distinctive tail flukes.
Distribution
In the western North Atlantic, humpback whales are widely distributed from north of Iceland, Disko Bay and west of Greenland, south to Venezuela and around the tropical islands of the West Indies. They have been reported from the central and eastern Gulf of Mexico. Summer ranges extend at least from New England north to the pack ice, and feeding concentrations may be found in any portion of this region. During winter, humpback whales migrate southward to the shallow borderlands of Bermuda, to the Bahamas, and to the West Indies to calve and mate.
Stranded Specimens
The most distinctive features of stranded humpback whales are 1) the ventral grooves, 14-22 in number, very wide and extending to the navel; 2) the tuberosities of the snout and lower jaw, often the sites of numerous barnacle colonies; 3) the long flippers (to nearly a third of the total body length); and 4) the distinctive rounded projection near the tip of the lower jaw.
If these characteristics are not sufficiently clear, the species may be identifiable by the characteristics of the baleen plates ([Table 2]).
Figure 38.—A series showing the extreme variability in dorsal fin shapes of humpback whales: ([a]) a small ridge, ([b]) slightly falcate, ([c]) triangular with a pronounced hump, ([d]) slightly rounded, ([e]) distinctly rounded, and ([f]) taller and more distinctly falcate. (Photos from northern West Indies by H. E. Winn [a, c, e] and C. McCann ; off Baja California by K. C. Balcomb [d]; and off St. Augustine, Fla. by D. K. Caldwell [f].)
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Large Whales Without a Dorsal Fin
BOWHEAD WHALE (B)
Balaena mysticetus Linnaeus 1758
Other Common Names
Greenland whale, Arctic right whale, great polar whale.
Description
Bowhead whales, so-called because of the high-arching jaws and the resultant contour of the head, reach a maximum length of about 65 feet (19.8 m). They are extremely robust in form.
When viewed from the side, some swimming bowhead whales show two characteristic curves to the back: the first extends from the tip of the snout to just behind the blowholes; the second, encompassing the entire back, begins just behind the head and extends all the way to the tail. This character may be present only in adult animals and may be more pronounced in males. Younger animals, particularly females, are often stubbier and somewhat barrel-shaped behind the head. In all animals the back is smooth, lacking even a trace of a dorsal fin.
The head of the bowhead whale is smooth, black, and without the bonnet and the "rock-garden," the colorful clusters of callosities characteristic of the black right whale. The blowholes are widely separated, and the blow emanating from them projects upward as two separate, distinct spouts. Though two separate columns sometimes may be visible under windless conditions in the blows of most mysticetes, this feature is exaggerated and is most characteristic in the bowhead and right whales.
Bowhead whales are black overall, except for a white "vest" of uneven coloration on the chin. Within that vest, near the sides of the white zone, there may be a series of grayish black to black spots, which on some animals have been likened to a string of beads. The vest is clearly visible when a surfacing animal is viewed from the front or the side or when the animals hang vertically in the water with the head on the surface and the tail flukes down, as they do during periods of early spring mating.
Natural History Notes
Bowhead whales are usually found singly or in groups of up to three animals, though fall concentrations may include up to 50 animals.
Bowhead whales sometimes breach, throwing most of the body clear of the surface and reentering with a resounding splash.
May Be Confused With
Bowhead whales are the only species of large whales found routinely in Arctic waters. Though other species, including some of the balaenopterid whales and the right whale, may venture north as far as the southern limits of the bowhead whale and beyond, they usually do so in the spring and summer, at a time when the bowhead whales are farther to the north. Even if they are encountered together, bowhead whales can be distinguished from all the balaenopterid whales by the absence of a dorsal fin. Bowhead whales have neither a fin nor the slightest trace of a dorsal fin or ridge, while all the balaenopterids have a dorsal fin; and their back is extremely smooth, like that of the right whale. The bowhead and right whales may be readily distinguished from one another by the characters listed below for stranded specimens.
Distribution
Though bowhead whales in the western North Atlantic were once distributed from Arctic waters, from the edge of the ice, south as far as the Strait of Belle Isle and the St. Lawrence River in such abundance that they were once referred to simply as "the whale," overwhaling through the 19th century until as recently as 1911 has severely reduced their numbers and restricted their modern range. Today in addition to the more abundant populations of the Bering, Beaufort, and Chukchi seas and the Sea of Okhotsk, there are populations off eastern Greenland and in Davis Straits, Baffin Bay, James Bay, and the adjacent waters. Within these ranges, bowhead whales move southward in front of the advancing ice floes and may be expected near the southern limits of their range from September or October through the early spring months. Populations in the western North Atlantic appear to be increasing slowly.
Stranded Specimens
In addition to the fact that their ranges may overlap only slightly if at all, bowhead whales may be distinguished from the other right whales of the western North Atlantic by differences in 1) primary distribution, 2) coloration, 3) lengths of the longest baleen plates, and 4) presence of callosities.
RIGHT WHALE (B)
Eubalaena glacialis (Borowski 1781)
Other Common Names
Black right whale, Biscayan right whale, Biscay whale, Nordcaper right whale.
Description
These right whales reach a length of about 53 feet (16.2 m).
The body is rotund and completely lacking a dorsal fin or a dorsal ridge. The upper jaw is long, narrow, and highly arched. The lips are similarly highly arched. The top of the head has a series of bumps or callosities, the largest one of which is known as the "bonnet," on the upper surface in front of the blowholes. Yellowish-brown lice and, less frequently, barnacles grow on the callosities. The color and extent of the callosities varies from one individual to the next.
The two blowholes are widely separated, resulting in the projection of the blow upward as two distinct spouts. The body is dark on the back, sometimes black, more often brown or mottled, usually has a region of white on the chin and belly, and sometimes has numerous small grayish-white scars of unknown origin. The baleen plates are up to 7.2 feet (2.2 m) long, very narrow, and variable in color from dark brownish through dark gray to black in color. When the animals swim, mouth agape near the surface, the baleen sometimes appears pale yellowish gray in color.
Natural History Notes
Right whales are usually not wary of boats and may often be approached very closely.
Like sperm and humpback whales, they usually throw their flukes high into the air when beginning a long dive.
Right whales feed primarily on copepods.
Historically, this whale was nearly exterminated by hunters, who took advantage of its slow speed and who knew that its carcass floats, to harvest these animals for their great yield of whalebone and oil. It was these characteristics which prompted whalers to dub these animals the "right" whales to kill (as opposed to the ones that were too fast to catch and sank when killed).
May Be Confused With
The distinct blow of the right whales and their smooth dark back, devoid of any traces of a dorsal fin, make it unlikely that the species will be confused with any other large whales except, perhaps, the bowhead whale. In the event that the expansion of their ranges again causes these two species to overlap in distribution, they can be distinguished from one another by the characteristics discussed on p. [49].
If only the flukes are seen as the animal begins a dive, right and bowhead whales may be distinguished from the other two species of large whales exhibiting this behavior, the sperm and the humpback, in this way: the flukes of right and bowhead whales are broad, pointed on the tips, greatly concave towards a deep fluke notch, and dark below: those of the sperm whale are more nearly triangular, while those of the humpback whale have a jagged irregular or rippled rear margin and are sometimes variously white below.
Distribution
Like its more northern relative, the bowhead whale, the right whale was once the object of a widespread and extensive whale fishery, which reduced the species to critically low numbers.
Though the former range of right whales is not clearly known, the species is thought to have been abundant from the Davis Straits south at least to the Carolinas and Bermuda and to have occurred in winter to Florida and perhaps into the Gulf of Mexico.
Currently, right whales are known from Iceland south to Florida. Animals move north along the eastern Florida coast between early January and late March. During this time the species has also been observed in the Gulf of Mexico off southwestern Florida and Texas. Right whales pass the coast of New England in fair numbers in spring and continue as far north as at least Nova Scotia. Right whales are also found off Iceland, though the migration routes to and from Iceland waters are not known. The recent apparent increases in numbers at the northern and southern coastal approaches in New England and Florida, respectively, lend credibility to the hopeful contention that the species will again recolonize its historical range.
Stranded Specimens
Stranded right whales can be easily identified by all the characters discussed on p. [49] and summarized in [Table 2].
Figure 49.—Closeup views of the heads of right whales off northeastern Florida ([top left] and [right]) and off Cape Cod, Mass. ([bottom left]) clearly showing the narrow upper jaw, the bonnet, and the widely separated blowholes. In the photo on the bottom left note the extremely long baleen plates, characteristic of bowhead and right whales. (Photos by N. Fain, courtesy of Marineland of Florida [top left and right]; and W. A. Watkins [bottom left].)
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SPERM WHALE (T)
Physeter catodon Linnaeus 1758
Other Common Names
Cachalot, Sea Wap (St. Vincent).
Description
Male sperm whales have been reported to reach a length of 69 feet (20.9 m), though today individuals larger than 50 feet (15.2 m) are rare. Females are much smaller, rarely exceeding 38 feet (11.6 m).
A sperm whale is among the easiest of whales to identify at sea even when comparatively little of the animal is visible. It has a huge head, which comprises from a fourth to a third of the animal's total length. (The proportion is considerably higher for males than for females.) The blunted "squarish" snout, which may project up to 5 feet (1.5 m) beyond the tip of the lower jaw, houses a large reservoir containing a high-quality oil called spermaceti.
The single blowhole is located well to the left of the midline and far forward on the head. As a consequence the small bushy blow, usually less than 8 feet (2.4 m), emerges forward at a sharp angle from the head and towards the left. Under good wind conditions this feature alone may permit positive identification of sperm whales even at considerable distances.
Sperm whales have a distinct dorsal hump, usually rounded in its appearance about two-thirds of the way back from the tip of the snout. Immediately behind the hump is a series of knuckles or crenulations along the midline. This hump and the crenulations are clearly visible when the animals arch the tail before beginning a dive. There is a ventral keel, which may also be visible as animals "sound" (dive). The flukes of sperm whales are broad and triangular in shape, are not concaved, but are deeply notched on the rear margin.
Sperm whales usually are dark brownish gray in color. The body has a "corrugated" or "shriveled" appearance. The belly and the front of the head may be grayish to off-white. The skin around the mouth, particularly near the corners, is white. The undersides of the flukes and flippers vary in color through numerous shades of browns and brownish grays.
Natural History Notes
Sperm whales may dive to depths in excess of 3,270 feet (996.7 m) for periods of an hour or more. As do most whales upon surfacing from a deep dive, sperm whales emit a single explosive blow and then, depending on the length of the dive, may remain on the surface for over 10 min and blow more than 50 times before beginning the next dive. Shorter periods on the surface and fewer blows are more common. Females may dive and remain on the surface for shorter periods of time than males. When beginning a deep dive, sperm whales throw their broad triangular flukes, dark on the undersides, high into the air.
Sperm whales may be found singly or in groups of up to 35 or 40 individuals. Older males are usually solitary except during the breeding season. During the remainder of the year large groups may be bachelor bulls (sexually inactive males) or nursery schools containing females and juveniles of both sexes. Sperm whales are seldom found in less than 600 feet (182.9 m) of water.
Sperm whales feed primarily on squid but may occasionally also take octopuses and a variety of fishes.
May Be Confused With
Because of their distinctive head shape and blow, sperm whales are unlikely to be confused with any other species when they can be closely examined. If only the back and tail flukes are seen, however, sperm whales may somewhat resemble humpback whales. Both species arch the back when beginning a dive, raising the fin or hump, and both throw the tail flukes. The most distinctive differences between the two species are tabularized on p. [40].
At sea the head of a sperm whale may also somewhat resemble that of an adult male northern bottlenosed whale, but this latter species is lighter brown in color, has a distinct beak and a prominent dorsal fin, and is rarely found south of lat. 42°N. In addition, the blowhole of the northern bottlenosed whale is located well back on the head and not—as in the sperm whale—on the front.
Distribution
Sperm whales are widely distributed in oceanic areas of the western North Atlantic. They may be encountered from Venezuela north at least as far as the Davis Straits, though they apparently avoid the polar ice fields. Distribution and migrations vary between males and females. Males range farther to the north, while females and immature males remain between lat. 30° and 50°N. Both groups shift northward during spring and summer and return to southern portions of their range in the fall. Adult males arrive off the New England coast in August. Those reaching the Newfoundland and Labrador coasts arrive from the deep sea, perhaps following the slope contours, in August and September. Males are abundant as far north as southeast Greenland and Iceland in summer. Some animals remain as late as November, but the majority migrate south to temperate or tropical waters in the early fall.
Historically the primary grounds in the western North Atlantic were those in all the following areas: the Grand Banks just southeast of the southern Grand Banks from lat. 30° to 40°N and long. 35° to 55°W, off the Carolinas, around the Bahamas, around many of the West Indies, and in the southwestern Caribbean.
Stranded Specimens
Stranded sperm whales should be easy to identify. The very narrow underslung jaw contains from 18 to 25 functional teeth, which fit into sockets in the upper jaw. The huge, distinctly box-shaped head and the position of the single blowhole to the left front of the head are unmistakable clues.
Medium-sized Whales With a Dorsal Fin
MINKE WHALE (B)
Balaenoptera acutorostrata Lacepede 1804
Other Common Names
Little piked whale, lesser rorqual, little firmer, sharp-headed finner, grampus (Newfoundland), gibord (Quebec).
Description
Minke whales are the smallest baleen whale species in the northern hemisphere, reaching maximum lengths of just over 30 feet (9.1 m). One of the most distinctive features of this species is an extremely narrow, pointed, distinctly triangular rostrum with a single head ridge, similar to but much sharper than that of the fin whale (hence the common name "sharp-headed finner"). Minke whales have a tall, falcate dorsal fin located in the latter third of the back, in about the same position as that of the sei whale, which often becomes visible simultaneously with the low, usually inconspicuous blow.
Minke whales are black to dark gray on the back and white on the belly and on the underside of the flippers. Portions of the underside of the flukes may be steel bluish gray. They have a diagonal band of white on each flipper, the extent and orientation of which varies individually.
Like the fin whale, minke whales (at least from the Pacific) sometimes have a chevron on the back behind the head and often have two regions of lightish-gray coloration on each side—one just above and behind the flippers; another just in front of and below the dorsal fin. These patches may be quite conspicuous on some animals, indetectable on others. These markings may also be present on Atlantic specimens, though they have not yet been documented. The baleen, which may be visible from close range when the animal is feeding, is mostly yellowish white with fine white bristles. The posterior plates (up to half) may be brown to black.
Natural History Notes
Minke whales are frequently found as single animals, pairs, or trios, though they may congregate in areas of food concentration in the northern seas during the spring and summer. They are more likely to be seen up close than their larger cousins—the blue, fin, and sei whales—because they often closely approach boats, particularly stationary boats, as if curious about them.
Minke whales may also approach very close to shore and often enter bays, inlets, and estuaries.
Like fin whales, they often arch the tail stock high into the air when beginning a long dive. However, they do not raise the flukes above the surface when beginning a dive.
Minke whales feed primarily on small shoal fish (herring, cod, pollack, and capelin).
Minkes sometimes breach, leaping completely clear of the water and entering smoothly, head first, or with a substantial splash like humpback whales.
May Be Confused With
When they are seen at relatively close range, minke whales can be readily distinguished from the other rorquals that have relatively tall, falcate dorsal fins (fin, sei, and Bryde's whales) by their considerably smaller size and by their distinctive white band on each flipper.
At a distance, however, positive identification may be difficult. Minke whales have a small, low, inconspicuous blow. Like sei whales, they frequently expose the dorsal fin simultaneously with the blow, but minke whales hump the tail stock much higher when beginning a long dive—more like fin whales.
From a distance, minke whales might also be mistaken for northern bottlenosed whales (or any of several other beaked whales with a similar dorsal fin). They can be distinguished by the differences in head shape, body color and markings, and behavior, detailed on p. [67].
Distribution
Minke whales are distributed in the polar, temperate, and tropical waters of the western North Atlantic. They are found from the pack ice south to at least Anguilla, Lesser Antilles, and the eastern Gulf of Mexico, though they appear to be most abundant in temperate waters north of the latitude of New York and are infrequently reported from tropical waters. At least some of the population migrates to the northern portions of their range in spring and back south in autumn. They often approach close to shore and enter river mouths, inlets, and estuaries.
Minke whales arrive along the Canadian coast in May or June. Some migrate as far north as Hudson Strait, where they remain until the freeze in October, November, or December. By December the majority of the population has begun to move to the south, although some animals remain behind so long as to become entrapped in the ice and die. Spring and summer concentrations along the Canadian coast correspond to concentrations of capelin, cod, and herring. Southern concentrations, also corresponding with concentrations of herring, extend farther offshore at least to the edges of the Grand Bank. Minke whales also summer off the south coast of western Greenland, which they probably reach from waters southwest of Iceland. Minke whales also occur in deep pelagic waters.
Stranded Specimens
Stranded minke whales can be most readily identified by: 1) their small size (to just over 30 feet [9.1 m]); 2) the transverse white bands on the flippers; 3) the yellowish-white baleen plates (up to half the posteriormost plates may be brown or black), 300-325 per side in number and having fine white bristles (the plates are up to 4.75 inches [12 cm] wide at the base and up to 8 inches [20.3 cm] long); and 4) by the 50-70 thin ventral grooves, ending well before the navel, often just even with the flippers.
Figure 63.—Three views of minke whales at sea. In all note the transverse band of white on the flippers and the sharply pointed head. Note the gray chevron visible on the back ([top]), the absence of a conspicuous blow and the appearance of the prominent dorsal fin on the surface while the blowholes are still exposed ([middle]), and the distinctive regions of light gray on the sides ([bottom]). (Photos from off San Diego, Calif. by G. E. Lingle [top]; from the northern West Indies by H. E. Winn [middle]; and from the western Pacific by Japanese Whales Research Institute, courtesy of H. Omura [bottom].)
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NORTHERN BOTTLENOSED WHALE (T)
Hyperoodon ampullatus (Forster 1770)
Other Common Names
None known.
Description
Northern bottlenosed whales reach a length of 32 feet (9.8 m) and are robust in form. They are characterized by a bulbous forehead, which is more pronounced on larger animals and most distinctive in adult males, and by the dolphinlike beak displayed in animals of all sizes and ages, which is sometimes visible as the animals surface steeply to breathe.
The blowhole is located in an indented area behind the bulbous forehead, and the blow emanating from it projects upward or slightly forward to a height of up to 6 feet (1.8 m), is bushy and is visible from a considerable distance under low wind conditions. The dorsal fin, located two-thirds of the way back on the back, reaches at least 12 inches (30.5 cm) in height and is distinctly falcate. The dorsal fin may be visible from a distance of several hundred meters.
Northern bottlenosed whales are usually brownish in color, though the markings change with age. Smaller animals are a uniform chocolate brown. Larger animals retain the chocolate brown color on the back but are often lighter on the sides and the belly and often have irregular patches or blotches of grayish-white coloration on the back and sides. Extremely large animals, presumably older males, often have a white head. The flippers and the undersides of the flukes are uniformly brown in color.
Natural History Notes
Northern bottlenosed whales often form tightly packed groups of up to 10 or more animals. This species holds the anecdotal record for the longest dives, having been reported by early whalers to remain submerged over 2 h. They are probably deep divers, feeding primarily on squid (though they may take fishes as well), and they rarely go in water shallower than 100 fathoms (183 m).
After a long dive, northern bottlenosed whales will sometimes remain on the surface for 10 min or more, blowing at regular intervals before making another dive. After the last blow of a series or when the animals are startled by a boat, they may show the tail flukes as they begin to dive. The flukes are not notched on the rear margin.
Northern bottlenosed whales have been observed to show curiosity about boats, coming to them from a considerable distance. They have also been observed to "lobtail," raising the tail flukes above the water and slapping them against the surface, and to jump clear of the water.
In the late 19th century, after stocks of bowhead whales were severely reduced by overwhaling, northern bottlenosed whales became a prime target of arctic whalers. They were sought because in addition to whale oil produced from the body blubber, the forehead of the species yielded quantities of spermaceti like that obtained from sperm whales.
May Be Confused With
Northern bottlenosed whales have a northerly and deep-water distribution. Within their range, they may be confused at a distance with minke whales, with sperm whales, or perhaps with North Sea beaked whales.
Minke whales (p. [63]) have a falcate dorsal fin located in approximately the same position as that of the northern bottlenosed whale. However, minke whales have a flathead in front of their two blow holes and are black to dark gray on the back.
Sperm whales (p. [57]) have a squarish head that may somewhat resemble that of an adult male northern bottlenosed whale. However, there are numerous characteristics which will permit these species to be distinguished even from a distance:
| NorthernBottlenosed Whale | Sperm Whale |
|---|---|
| BLOW | |
| Low and bushy; projectsupward from indentation ontop of head. | Low and bushy, projectsobliquely forward from leftside of head; usually lessthan 8 feet (2.4 m). |
| COLORATION | |
| Lighter brown; adults splotchedwith grayish white;body smooth. | Brownish gray; body appearswrinkled. |
| FLUKES | |
| Rarely notched; seldom raisedon long dive. | Notched; raised on long dive. |
| HEAD | |
| Tapering in younger animals;bulbous in adults;white in older animals; beaked. | Squarish, long, all black;bbeakless. |
A further aid to distinguishing northern bottlenosed and sperm whales at sea is the fact that the sperm whales that are found in areas where northern bottlenosed whales are encountered are usually older, larger males from 40 to 60 feet (12.2 to 18.3 m) long. Northern bottlenosed whales do not exceed 32 feet (9.8 m).
Northern bottlenosed whales may also be confused with the poorly known North Sea beaked whale (p. [82]). When they can be examined at close range, however, northern bottlenosed whales should be distinguishable on the basis of the distinctly bulbous forehead.
Distribution
In the western North Atlantic, northern bottlenosed whales are restricted to Arctic and north temperate waters, where they most commonly occur in offshore areas. They have been reported from Davis Straits and the entrance to Hudson Strait, the Gully southeast of Sable Island, and as far south as Narragansett Bay, R.I.
In the spring and summer they concentrate near the northern limits of their range, occasionally visiting deep channels of the Gulf of St. Lawrence and eastern Newfoundland in summer. During these seasons they may extend to the edge of the pack ice.
In the fall and winter the bulk of the population migrates southward. Many probably winter in the Labrador Sea while others move farther southward and farther offshore.
Stranded Specimens
Like the beaked whales discussed on p. [70] through [83], the northern bottlenosed whales have no notch in the tail flukes, have two throat grooves forming a V-shape on the chin, and have only two teeth in the lower jaw, with those teeth emerged from the gums only in adult males. These teeth may have sometimes fallen out of older males, but the tooth sockets should still be visible in the gums.
NOTE: Some specimens—both male and female—will be found to have a series of vestigial teeth the size of toothpicks in the upper and/or lower jaws. Similar vestigial teeth, 5-40 in number, sometimes occur in goosebeaked whales (p. [70]). Further when they are prepared for museum collections, the lower jaws of adult northern bottlenosed whales may be found to contain a second pair of teeth just behind the first.
Northern bottlenosed whales may be distinguished from the remainder of the beaked whale family, however, by the extremely robust body, by the bulbous forehead, which is more extensively developed in larger animals, particularly males, and by the pronounced dolphinlike beak.
Figure 68.—Views of the heads of male northern bottlenosed whales off Nova Scotia. Note the distinctive beak ([right]) and the bulbous forehead, features which develop with age and are most pronounced in adult males. In the animal on the [left], note also the low bushy blow emanating from the indented area on the top of the head. (Photos by H. E. Winn.)
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GOOSEBEAKED WHALE (T)
Ziphius cavirostris G. Cuvier 1823
Other Common Names
Ziphius, Cuvier's beaked whale, grampus (St. Vincent) (see also p. [96]).
Description
Goosebeaked whales reach a length of 23 feet (7 m). Females are slightly larger than males of the same age. Calves are probably less than about 6 feet (1.8 m) at birth. The head is small relative to the body length and, when viewed laterally, is slightly concaved or scooped on the upper margin. The cleft of the mouth is small, smaller than in any other species of beaked whales. The beak is indistinct in larger individuals. There is a distinct indentation on the back behind the head. Two teeth are found at the tip of the lower jaw of adult males only.
The dorsal fin is relatively tall and distinct, to at least 15 inches (38.1 cm), smoothly falcate, and located well behind the midpoint of the back. The blowhole is located far forward on the top of the head. The blow, which may project slightly forward and slightly off to the left, is usually low and inconspicuous. Though the first blow after a long dive may be more distinct, even it is rarely visible even under good wind conditions for more than a few hundred yards.
Descriptions of the color pattern vary. Individuals may be dark rust brown, slate gray, or fawn colored on the back and generally lighter on the belly. Some appear dark in both regions, still others—particularly youngsters—appear lighter gray or tan on the belly. The body is frequently covered with white or cream-colored blotches (particularly on the belly). The tail flukes are dark on the bottom. The head is frequently paler in color. Old males have a distinct white head and are frequently extensively scarred.
Natural History Notes
Goosebeaked whales frequently occur in groups of from 10 to as many as 25 individuals. They have been reported to jump clear of the water. They are presumably deep divers and are known to stay down for more than 30 min. When they begin a deep dive, they often raise their tail flukes above the surface and dive nearly vertically. Goosebeaked whales feed primarily on squid.
May Be Confused With
So little is known of the external appearance and behavior of the living beaked whales at sea that all the species may easily be confused.
Goosebeaked whales are larger than all other beaked whale species with the exception of the northern bottlenosed whale. Upon close examination they may be distinguished from the northern bottlenosed whale by the lighter coloration of the head, reaching an extreme in the white head of adult males. (See p. [67] and [Fig. 75].)
Distribution
As with other species of beaked whales seldom encountered or at least seldom positively identified at sea, the distribution of goosebeaked whales is poorly known and must be constructed from records of stranded specimens. Such records, often involving sick individuals that may have washed ashore from considerable distances, may give an inaccurate picture of normal ranges.
In general, stranding reports suggest that goosebeaked whales are sparsely but widely distributed in nonpolar latitudes. They appear to be primarily tropical in distribution, though they venture into temperate areas in summer. They have been reported from Massachusetts and Rhode Island south to Florida and thence to the islands of the West Indies. They are frequently stranded along the Florida coast and are not an uncommon species in the extant whale fishery of the Antillean Islands. The fact that goosebeaked whales strand more frequently than other beaked whales may reflect either a greater abundance or a greater tendency to approach close to shore.
They are probably primarily an offshore species.
Stranded Specimens
To be positively identified, stranded goosebeaked whales in an advanced state of decomposition may require museum preparation and examination of the skull and teeth. Fresh specimens may be tentatively identified by the characters illustrated in the figures.
Figure 75.—Stranded goosebeaked whales, an adult male from northern California ([top]) and an immature female from the northeastern Gulf of Mexico ([bottom]). Note the brownish color of the back, marked in the adult animal by blotches of lighter gray and numerous scratch marks, presumably tooth rakes. Note also the mouth cleft, shorter in this species than in any other beaked whale species, and the slightly concave appearance to the upper margin of the head. The beak is usually less developed in large animals. The [inset photo] shows a ventral view of the tip of the lower jaw of an adult male from the east coast of Florida. The two teeth of the species are emerged above the gum only in adult males. (Photos by W. J. Houck [top], Florida's Gulfarium [middle], and W. A. Huck, courtesy of Marineland of Florida [inset].)
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OTHER BEAKED WHALES (T)
Mesoplodon spp.
Other Common Names
Grampus (St. Vincent) (see also p. [96]).
Description
In addition to the northern bottlenosed whale (p. [67]) and the goosebeaked whale (p. [70]), four other species of beaked whales have been reported from the western North Atlantic. All four species are known primarily from stranded specimens and have been rarely encountered at sea. Therefore statements of range are usually limited to inferences from locations of strandings, and information on appearance and habits of the species in the wild is almost totally lacking.
The infrequent encounters with beaked whales at sea may result from such factors as 1) a low inconspicuous blow, 2) avoidance of ships, and/or 3) distribution in small groups in offshore areas well outside the normal boating lanes.
The following descriptions will aid primarily in identifying stranded specimens. Though subtle differences in ranges, color patterns, and dorsal fin shapes and positions may be helpful in narrowing the choices of living animals, the species will continue to be extremely difficult to distinguish from one another in the brief encounters typical at sea until additional data are collected.
The beaked whales have the following characteristics in common: 1) two small creases forming a V-shape on the throat, 2) the absence of a conspicuous notch on the rear margin of the tail flukes (some specimens have a slight indentation), and 3) the absence of functional teeth in all except adult males. Adult males have a single pair of teeth in the lower jaw, the position and description of which help to identify the species. The teeth of females are not functional and only rarely emerge from the gums. Therefore, if a stranded animal is an adult male, its species can be determined by the position and description of the teeth. For example, in Mesoplodon mirus, the teeth are located near the tip of the lower jaw; in M. europaeus, they are located about a third of the way from the tip of the snout to the corner of the mouth; in M. bidens, they are nearly half way from the tip of the snout to corner of the mouth; and in M. densirostris, they are located in large prominences near the back of the mouth.
If the animal is a female or an immature male, however, museum preparation and examination might be required before the species can be positively determined. The following four sections summarize characters of western North Atlantic beaked whales.
Figure 78.—Adult male beaked whales, showing the body profile and the relative positions of the teeth. Remember that the teeth of females and immature males are concealed beneath the gums. (Drawing by L. Winn.)
TRUE'S BEAKED WHALE (T)
Mesoplodon minis True 1913
Other Common Names
None known.
Description
True's beaked whales reach a length of at least 16 feet (4.9 m) long. They are chunky in midbody and narrow rapidly towards the tail, closely resembling goosebeaked whales (p. [70]). In overall body shape, the head is small with a slight indentation in the area of the blowhole, a slight bulge to the forehead, and a pronounced beak. The flippers are small (from one-fourteenth to one-tenth the body length). The dorsal fin is small, slightly falcate, located in the latter third of the back, and followed by a pronounced ridge on the tail stock. The flukes, which sometimes contain a very slight notch, are broad (to almost one-fifth the body length).
True's beaked whales are dull black to dark gray on the back, lighter slate gray on the sides, and white on the belly. The body is frequently covered with light colored spots or splotches and bears numerous pairs of scratch marks, presumably tooth rakes ([Fig. 76]).
The flippers are all black and are attached in the dark coloration of the animal's side. The flukes are dark above and below.
May Be Confused With
True's beaked whales are most likely to be confused with goosebeaked whales (p. [70]) but may also be confused with any of the other beaked whales species (p. [74] and [Fig. 78]).
Distribution
True's beaked whales appear to be primarily temperate in distribution. They have been reported from Cape Breton Island, Nova Scotia south as far as Flagler Beach in Florida. Northernmost records are for summer months.
The range of True's beaked whales overlaps with that of the Antillean beaked whale but is more northerly.
Stranded Specimens
The teeth of adult male True's beaked whales may be visible near the tip of the lower jaw, a characteristic shared with the goosebeaked whale (p. [70]) and the northern bottlenosed whale (p. [67]). Both these other species reach substantially greater maximum lengths than True's beaked whales, however, and should be readily distinguishable by this and the number of other highly distinctive characteristics of each species.
Females and subadult males may be confused with any of the beaked whales species (p. [74] and [Fig. 78]).
ANTILLEAN BEAKED WHALE (T)
Mesoplodon europaeus (Gervais 1855)
(equals M. gervaisi [Deslongchamps])
Other Common Names
Gulfstream beaked whale, Gervais' beaked whale.
Description
Antillean beaked whales reach a length of at least 22 feet (6.7 m). They are slender in form and appear somewhat laterally compressed (i.e., taller than they are wide). The head is extremely small and tapers rapidly to a narrow beak. The flippers are small (to about one-twelfth the body length) with their origin well down on the sides of the body. The dorsal fin is small, located behind the midpoint of the back, and variable in shape from falcate to triangular. The flukes are less than one-fifth the body length and are not notched.
Antillean beaked whales are dark grayish black on the back and sides, slightly lighter on the abdomen. The flukes are dark gray above and below.
Natural History Notes
Antillean beaked whales are probably primarily oceanic in distribution and are known to feed on squid.
May Be Confused With
Antillean beaked whales may be confused with any of the other beaked whales though they are larger than all except the northern bottlenosed whale (p. [67]) and the goosebeaked whale (p. [70]).
Distribution
Antillean beaked whales have been reported stranded from the latitude of Long Island, N.Y. south to Florida, thence into the Caribbean and the Gulf of Mexico.
Stranded Specimens
The teeth of Antillean beaked whales are located at the suture of the mandible, about one-third of the way from the tip of the snout to the corner of the mouth ([Fig. 78]).
DENSE-BEAKED WHALE (T)
Mesoplodon densirostris (Blainville in Desmarest 1817)
Other Common Names
None known.
Description
Dense-beaked whales reach a length of at least 17 feet (5.2 m). The body is distinctly spindle-shaped. The head, the contour of which is the most distinctive characteristic of this species, is marked by a prominent rise, located near the angle of the gape on each side. This rise, which bears the teeth, gives a peculiar high, arching contour to the mouth ([Fig. 84]), particularly in adult males.
The flippers are small (one-eleventh to one-tenth the body length) and have their origin in the lighter color of the lower sides. The dorsal fin varies from small and triangular to nearly falcate and pointed on the tip. It is located behind the midpoint of the back. The flukes are from one-sixth to one-fifth the body length, are seldom notched, and occasionally even bulge slightly backwards near the center of the rear margin.
Dense-beaked whales are black or charcoal gray on the back, slightly lighter on the abdomen. They are somewhat blotched with grayish white and are often extensively scratched or scarred. The flippers are lighter than the back. The flukes are dark above, light below.
Natural History Notes
From stomach contents of stranded animals dense-beaked whales are known to feed on squid.
May Be Confused With
Adult male dense-beaked whales can be separated from the other beaked whales by the high, arching contour to the corners of the mouth. If there is no adult male in the group, however, dense-beaked whales may be confused with any of the other beaked whales species.
Distribution
Dense-beaked whales have been reported from Peggys Cove, Nova Scotia south to Florida. From all accounts, this species appears widely but sparsely distributed in warm temperate seas.
Stranded Specimens
Adults of this species should be distinguishable by the highly distinctive contour of the mouth. The teeth, located in the high rise of the mouth, are oriented slightly backwards.
Figure 84.—Views of the heads of dense-beaked whales. Females ([bottom]) and immature males have a slight curvature to the rear of the mouth. As they mature, males ([middle] and [top]) begin to display the two arching prominences near the corners of the mouth which give the characteristic contour to the mouth. The teeth are located in these prominences and are oriented slightly backwards. (Photos from northeastern Florida by W. A. Huck, courtesy of Marineland of Florida [top and middle] and by J. G. Mead [bottom].)
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NORTH SEA BEAKED WHALE (T)
Mesoplodon bidens (Sowerby 1804)
Other Common Names
Sowerby's beaked whale.
Description
North Sea beaked whales reach a length of at least 16.5 feet (5 m). The body is distinctly spindle-shaped, but apparently more robust near midbody than that of the dense-beaked whale. The head is characterized by a pronounced bulge in front of the blowhole, a slightly concave forehead, and a moderate to long beak. The flippers are relatively long (one-eighth to one-ninth the body length). The dorsal fin is reportedly tall and variable in shape from triangular to slightly falcate and is located just behind the midpoint of the back. The flukes are not notched but are sometimes quite concave on the rear margin.
Adult North Sea beaked whales are dark charcoal gray on the back with white spots overall. Young animals are also dark charcoal gray on the back but are lighter on the belly and are unspotted. The flukes of adults are dark above and below. Those of young are dark above, lighter below.
Natural History Notes
North Sea beaked whales are known to feed on squid.
May Be Confused With
North Sea beaked whales are the most northerly species of beaked whales. No other species is very likely to be encountered in the same area.
Distribution
North Sea beaked whales have been reported in the offshore waters from the latitude of New England north perhaps to the pack ice. Individuals are occasionally drawn to the coasts of Newfoundland in summer, presumably by concentrations of squid, a known food item.
Stranded Specimens
The teeth of North Sea beaked whales are located about midway between the tip of the snout and the corner of the mouth. Except for this characteristic and their northerly distribution, however, this species might easily be confused with any other of the beaked whales species.
KILLER WHALE (T)
Orcinus orca (Linnaeus 1758)
Other Common Names
Blackfish (see also pilot whales, p. [91] and [94]), sword fish (Canada), grampus (see p. [96]), whitefish (St. Vincent), Espladon (Quebec).
Description
Killer whales are the largest member of the dolphin family. Adult males reach a length of at least 30 feet (9.1 m) and are robust in form. One specimen of 31 feet (9.5 m) was recorded for the western North Pacific. Females are considerably smaller and less stocky. Newborn are approximately 7-8 feet (2.1-2.4 m) long. Killer whales have large paddle-shaped flippers.
The most distinctive field character of the species is the dorsal fin. In adult males it is extremely erect and may be as much as 6 feet (1.8 m) tall. Though the fin of females and immature males is less than 3 feet (0.9 m) tall, it is nonetheless taller even in these animals than in any other cetacean species and is distinctly falcate and pointed on the tip.
Killer whales are basically black with an extensive region of white on the undersides extending from the lower jaw to the anal region with a branch extending onto the flanks behind the dorsal fin. There is an oval white patch on the side of the head just above and behind the eye. In newborn and very young calves, these regions may be tan to lemon yellow in color. Most animals have a light-gray saddle marking just behind the dorsal fin. The undersides of the flukes are usually white. Both all-black and all-white animals have been reported.
Natural History Notes
Killer whales travel in groups of from a few to 25 or 30 individuals, though herds of 150 have been reported. Males appear polygamous, and females and young may form groups separate from young bachelors and bulls.
Killer whales are extremely fast swimmers, capable of reaching top speeds of 25 knots or more, and have been reported "porpoising" and breaching. Individuals and entire groups have also been reported "spy-hopping," or "pitchpoling," behaviors which consist of hanging vertically in the water with the head and much of the body (to just behind the flippers) exposed above the surface.
Killer whales feed on squid, fishes, sea turtles, seabirds, and marine mammals.
Controversy still continues over whether or not killer whales pose a threat to man. Documented attacks of killer whales on boats are rare and have usually been provoked (i.e., harpooning or attempts to capture). Only two uncertain instances of attacks in the wild have been reported, but all divers and mariners should be cautioned that this powerful animal is perfectly capable of doing tremendous damage and should not be provoked.
May Be Confused With
Because of its very distinctive dorsal fin, body shape, and coloration, the killer whale is not likely to be confused with any other whale when it can be examined at close range or when an adult male is present in the group. Pods of females and immature animals, however, may be confused with false killer whales or with grampus. The killer whales may be distinguished from false killers by the following differences:
| Killer Whale | False Killer Whale |
|---|---|
| BODY SHAPE | |
| Chunky. | Slender. |
| BODY COLOR | |
| Black with white on belly,flank, and head. | All black with some gray onbelly. |
| DORSAL FIN | |
| Very tall and erect in adultmales; tall and slightly backcurved in female. | Shorter, slender, stronglyfalcate. |
| HEAD SHAPE | |
| Broad, rounded. | Tapered, slender. |
| FLIPPER SHAPE | |
| Paddle-shaped. | Moderately long withcharacteristic hump nearmiddle on forward margin. |
| LENGTH | |
| To at least 30 feet (9.1 m). | To at least 18 feet (5.5 m). |
Furthermore, false killer whales are the only "blackfish" which are known to ride the bow wave of a ship.
Grampus have a tall dorsal fin (15 inches [38.1 cm]) which is very similar in appearance to that of adult female and juvenile killer whales. But grampus have much lighter coloration, from slate gray to nearly all white, and larger animals are covered with numerous scratches. Upon closer examination they can be further distinguished from killer whales by a crease in the front of the head dividing the melon into two distinct sections. Grampus are considerably smaller, to about 13 feet (4 m) maximum length.
Distribution
In the western North Atlantic killer whales have been reported from the polar pack ice south to Florida and St. Vincent, Lesser Antilles, and into the Gulf of Mexico at least as far as Texas, though they are far more common in the cooler waters from about New Jersey north. Throughout their range, killer whales seem to prefer coastal areas and often enter shallow bays, estuaries, and river mouths in search of food.
Migrations of the species are probably closely tied to movements of their food supply. They annually arrive on the coast of New England with the tuna. Along the Canadian coasts, where distribution and migrations have been described in some detail, killer whales appear to move inshore in spring and summer. Many arrive off the east coast of Newfoundland in June, the Strait of Belle Isle in June and July, and slightly later along the Labrador coast and Arctic waters. They are found around the loose ice in April, presumably feeding on harp seals, Pagophilus groenlandicus, and hooded seals, Cystophora cristata, and are frequent in the St. Lawrence estuary in spring and autumn following the movements of the white whales. The northward movements in spring also coincide with migrations of balaenopterine whales, which have also been reported among the food items. Killer whales may remain in arctic or subarctic waters until driven out by new forming ice in October and November. Though the migration has not been as thoroughly described, killer whales apparently begin shifting southwards in autumn.
Stranded Specimens
Stranded killer whales should be readily identifiable by the robust body, the distinctive body markings, and in larger animals the tall dorsal fin. Killer whales have from 10 to 12 large, prominent teeth on each side of the upper and lower jaws.
Figure 88.—A small herd of killer whales off southern California ([top]) and details of an adult male from that herd ([middle]) and of females or immature males off Islas San Benito, Baja California ([bottom]). Adult males have a tall erect dorsal fin, which may be more than 6 feet (1.8 m) tall, while the fins of females and immature males are less than 3 feet (0.9 m) tall, distinctly falcate, and pointed on the tip. Both sexes frequently have a grayish-white region, called a "saddle," behind the dorsal fin. (Photos by T. Dohl [top and middle] and S. Leatherwood [bottom].)
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FALSE KILLER WHALE (T)
Pseudorca crassidens (Owen 1846)
Other Common Names
Mongoose (St. Vincent).
Description
False killer whales in the western North Atlantic reach a length of at least 18 feet (5.5 m). Males are slightly larger than females. Calves from 5 to 7 feet (1.5 to 2.1 m) may be seen at any time throughout the year.
The dorsal fin, located just behind the midpoint of the back, is from 7 to 16 inches (17.8 to 40.6 cm) tall, falcate, and variable to sharply pointed on the tip. The flippers are characterized by a broad hump on the front margin near the middle, a characteristic which is diagnostic for the species.
The body of the species is all black except for a blaze of gray on the belly between the flippers. This blaze varies from barely visible to light grayish white similar to but generally fainter than that of pilot whales. The body is long and slender, and the head is narrow and gently tapered from the area of the blowhole forward.
Natural History Notes
False killer whales are a social form and may occur in herds of up to at least 100 individuals. They often jump clear of the water and frequently ride the bow waves of vessels. They are the only "blackfish" which are known to do so. False killer whales feed primarily on squid and large fishes and are notorious for their habit of stealing fish from the lines of fishermen. The large prominent teeth may be visible on a swimming animal.
May Be Confused With
False killer whales may be confused with killer whales, pilot whales, or the smaller, poorly known pygmy killer whale (p. [138]) and many-toothed blackfish (p. [142]).
The characteristics distinguishing the species from the killer whale are tabularized on p. [84]; its differences from the pilot whales are summarized on p. [92].
At sea, false killer whales are distinguishable from the other two species primarily by their larger size and differences in coloration. False killer whales are up to 18 feet (5.5 m) in length. Pygmy killer whales and many-toothed blackfish reach only 8-9 feet (2.4-2.7 m) in length. Pygmy killer whales have an extensive region of white on the belly which may extend onto the sides and both pygmy killer whales and many-toothed blackfish have a distinctive white region on the lips, usually lacking or indistinct on false killer whales.
Neither of the smaller species of blackfish has been reported to ride bow waves.
Distribution
False killer whales are widely distributed in the pelagic tropical, subtropical, and warm temperate waters of the western North Atlantic. They have been reported from off Maryland south along the mainland coasts of North America, in the Gulf of Mexico from Cuba and the Lesser Antilles, and from the southeast Caribbean Sea. The species has been reported from Venezuela.
Stranded Specimens
Stranded false killer whales can be positively identified by: 1) the large size (to 18 feet [5.5 m]); 2) the slender body tapering rapidly to a long slender head; 3) the markedly long mouth, with from 8 to 11 large, conspicuous teeth in each side of each jaw recalling those of the killer whale, but circular and not, as in killer whales, elliptical; 4) the unusually shaped flipper bulging conspicuously on the forward margin.
For comparison with "blackfish" of similar size (the pilot whales) see p. [92] and [94].
False killer whales do not appear to occur frequently in coastal waters, sandy bays, or estuaries, though entire herds have stranded in such areas. Records from throughout the range suggest that the species has an oceanic distribution.
ATLANTIC PILOT WHALE (T)
Globicephala melaena (Traill 1809)
Other Common Names
Northern pilot whale, long-finned pilot whale, pothead, blackfish, calling whale, caa'ing whale.
Description
Male Atlantic pilot whales reach an average length of at least 20 feet (6.2 m). Females are slightly smaller, probably not exceeding 18 feet (5.5 m). Young are 5-7 feet (1.5-2.1 m) at birth.
The head is thick and bulbous, a characteristic which reaches an extreme in the development of the head of adult males (prompting the common name "pothead"). The flippers are long (to one-fifth of the body length, or more) and sickle-shaped. The tail is dorsally thickened just in front of the flukes.
The dorsal fin of this species is one of its most distinctive characteristics. It is low in profile, has a long base, is set far forward on the animal's back, and is falcate to "flaglike" in appearance. The dorsal fin of adult males reportedly has a thicker leading edge and a rounder form than that of the female.
Atlantic pilot whales are black on the back and sides (prompting the common name "blackfish") but have an anchor-shaped patch of grayish white on the chin and a gray area on the belly, both of which are variable in extent and intensity. Some larger animals have a gray saddle behind the dorsal fin, though this zone of color is found more frequently in short-finned pilot whales. Young animals are often a lighter medium gray.
Natural History Notes
Atlantic pilot whales may occur in herds of 200 animals or more, though herds of 50 or fewer (4-6) are more common. They are sometimes found in association with Atlantic white-sided dolphins.
Pilot whales are sometimes found hanging vertically in the water with the head and part of the back out of the water in what has been called "spy-hopping" or "pitchpoling." Individuals frequently lobtail. Pilot whales infrequently breach, a behavior which is usually confined to younger animals. They do not ride bow waves.
Atlantic pilot whales feed primarily on squid but also take cod and other fishes. A Pacific pilot whale, a closely related species, was found by radio telemetric studies to be capable of diving to 2,000 feet (609.6 m).
Atlantic pilot whales were formerly the object of an active shore fishery off Newfoundland (1950-1971). In addition, entire herds and, less frequently, individuals are sometimes stranded.
May Be Confused With
Atlantic pilot whales are most likely to be confused with false killer whales, with which they share the waters from off Virginia to those off Maryland. The two species may be distinguished by the following characteristics:
| Atlantic Pilot Whale | False Killer Whale |
|---|---|
| SHAPE OF HEAD | |
| Thick and often squarish inlarger animals. | Slender, gently taperingmouth long. |
| SHAPE OF BODY | |
| Robust. | Long and slender. |
| DORSAL FIN | |
| Broad-based and falcate. | Slender, tall, falcate, andpointed on tip. |
| COLORATION | |
| Black with gray saddlesometimes evident behinddorsal fin and gray regionon chin and belly. | Mostly black with gray blazeof variable extent andintensity on belly betweenflippers. |
| BEHAVIOR | |
| Will not ride bow waves;seldom breaches. | May ride bow waves, often"porpoises" and breaches. |
| RANGE | |
| Temperate waters from atleast North Carolina north. | Temperate seas from at leastMaryland south. |
In the extreme southern portion of their range, Atlantic pilot whales may be confused with short-finned pilot whales with which they have only a limited seasonal common range. Characters distinguishing these species are subtle and may not be adequate to permit them to be distinguished at sea. For purposes of this guide it is generally that pilot whales living north of lat. 38°N (Virginia coast) are Atlantic pilot whales and those living south of lat. 38°N are short-finned pilot whales.
Distribution
Atlantic pilot whales, the northernmost of the two pilot whales species, are found in winter from the Grand Banks south as far as North Carolina and in summer from Iceland and Greenland south to the New Jersey coast. Winter concentrations of pilot whales may be found off the Newfoundland coast and near Cape Cod, Mass. Atlantic pilot whales are distributed both in coastal waters and in deep waters off the continental shelf.
Stranded Specimens
As discussed above, individuals and groups of pilot whales frequently strand themselves for still incompletely understood reasons. They may be identified as pilot whales primarily by: 1) the robust body and bulbous head, which is often squarish in adult animals, and 2) the broad-based, falcate dorsal fin located far forward on the back. Accurate determination of the pilot whale species involved in the stranding may require museum preparation of the skull and detailed examination of its characteristics. Preliminary identification may be made, however, based on the following:
| Atlantic Pilot Whale | Short-Finned Pilot Whale |
|---|---|
| FLIPPER LENGTH | |
| To one-fifth body length,or more. | To one-sixth body length, orless. |
| NORMAL RANGE | |
| From North Carolina north. | From North Carolina south. |
| TEETH | |
| 8-11 per row. | 7-9 per row. |
Figure 98.—Atlantic pilot whales frequently "lob tail" (raise the tail flukes above the surface and slap them against the water) ([top]) and pitchpole or spy-hop (hang vertically in the water with the head up and the tail down) ([bottom]). (Photos from the North Atlantic by H. E. Winn.)
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SHORT-FINNED PILOT WHALE (T)
Globicephala macrorhynchus Gray 1846
Other Common Names
Blackfish (see also p. [84], [91], and [94]).
Description
Male short-finned pilot whales of the western North Atlantic reach lengths of at least 17.5 feet (5.3 m). Females are reportedly slightly smaller than males (recorded only to 15.5 feet [4.7 m]).
The head, somewhat like that of the Atlantic pilot whales (p. [91]), is thick and bulbous, a characteristic which reaches its extreme in the development of a flattened or squarish appearance to the front of the head in mature males (see Fig. 101). In very old males the melon may overhang the mouth up to several inches. The flippers are shorter than those of the other pilot whale species of the western North Atlantic (thus the common name short-finned pilot whale), reaching only one-sixth of the body length or less. The tail is dorsoventrally thickened just in front of the flukes.
The dorsal fin, like that of the Atlantic pilot whale, is one of the species' most distinctive characteristics. It is low in profile, has a long base, and is set far forward on the animal's back.
Short-finned pilot whales are all black on the back sides and most of the belly with an anchor-shaped patch of gray on the chin and a gray area of varying extent and intensity on the belly. These areas are less vivid and extensive than those on Atlantic pilot whales. Younger animals are lighter, often medium gray.
Natural History Notes
Short-finned pilot whales are known to occur in groups of 60 animals or more, though smaller groups are more common. They have been reported pitchpoling (spy-hopping), lobtailing, and—rarely—breaching.
Short-finned pilot whales feed on squid and fish.
May Be Confused With
In the tropical portion of their range, short-finned pilot whales may be confused with pygmy killer whales (p. [138]) and many-toothed blackfish (p. [142]). They may be distinguished from both species primarily by their distinctive dorsal fin and the bulbous-to-squarish head. Both pygmy killer whales and many-toothed blackfish have dorsal fins, which are more falcate, slender, and pointed on the tip, and have longer, slenderer heads.
Throughout their range short-finned pilot whales may be confused with false killer whales. The two species may be distinguished by the same differences which distinguish Atlantic pilot whales from false killer whales (p. [91]).
In the extreme northern portion of their range, short-finned pilot whales may be confused with Atlantic pilot whales. The two species may be distinguished by differences itemized on p. [93].
Distribution
Though short-finned pilot whales are known from Delaware Bay, their normal range appears to extend from Bermuda and Cape Hatteras (Virginia in summer) south to the Venezuelan coast. They have been reported for the Gulf of Mexico, the Caribbean, and the islands of the West Indies.
Stranded Specimens
Stranded short-finned pilot whales may be confused with any of the species itemized under living animals. They may be identified as pilot whales primarily by the robust body and bulbous head, often squarish in adult animals, and the broad-based, falcate dorsal fin located well forward on the animal's back. Accurate determination of the pilot whale species involved may require museum preparation of the skull and detailed examination of its characteristics. Preliminary identification may be made, however, on the basis of the following:
| Atlantic Pilot Whale | Short-Finned Pilot Whale |
|---|---|
| DISTRIBUTION | |
| Primarily North Carolinanorth. | Primarily North Carolinasouth. |
| FLIPPERS | |
| To one-fifth body length,or more. | To less than one-sixth bodylength. |
| TEETH | |
| 8-11 per row. | 7-9 per row. |
Figure 101.—Short-finned pilot whales have from 7 to 10 teeth in each side of each jaw. The bulbous forehead of the species is far less pronounced in females and immature males ([left]). The head of mature males is extremely "squarish" and may overhang the lower jaw by several inches ([right]). (Photos from Aquatarium [left] and southeastern Florida by D. K. Caldwell [right].)
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GRAMPUS (T)
Grampus griseus (G. Cuvier 1812)
Other Common Names
Risso's dolphin, gray grampus, white-headed grampus, mottled grampus, Risso's porpoise, hard knocks (St. Vincent), white blackfish (Cape Cod).
Description
Grampus reach a maximum length of about 13 feet (4 m). The body is robust, particularly in front of the dorsal fin, and lacks a distinct beak. The head is somewhat bulbous and is marked on the front by a V-shaped crease with the point downwards, which divides the melon into two parts. The flippers are long and pointed on the tips. The dorsal fin, located at about the midpoint of the body, is tall, to 15 inches (38.1 cm) or more, and distinctly falcate. The body narrows rapidly behind the dorsal fin and the tail stock is quite narrow. The flukes are broad, concaved on the rear margin, and deeply notched.
The bodies of grampus are a uniform light gray at birth. As the animals age, their color darkens to almost black with distinctive regions of grayish white on the belly and chest. The body of older adults is cream white or silver gray, particularly on the head, with numerous scars, presumably from encounters with other grampus and perhaps with the squid, which are one of the species' major food items.
The flippers, dorsal fin, and tail flukes usually remain dark even in adults.
Natural History Notes
Grampus are found in herds of up to several hundred individuals and may be seen "porpoising" (leaping from the water) as they surface to breathe, and breaching. They sometimes ride the bow waves of a boat.
Grampus feed on fish and squid.
May Be Confused With
From a distance grampus are most easily confused with Atlantic bottlenosed dolphins. They may be most readily distinguished by the following differences:
| Grampus | Atlantic Bottlenosed Dolphin |
|---|---|
| SIZE | |
| To 13 feet (4 m). | Rarely to 12 feet (3.7 m);usually less than 10 feet(3.1 m). |
| BODY COLOR | |
| Young are uniform lightgray; older animals darkwith grayish regions onchest and belly; veryold animals white andscarred. | Dark gray on body; lightergray on sides; white or pinkon belly; may appear brownishin water. |
| DORSAL FIN | |
| To 15 inches (38.1 cm);sharply falcate; pointedon tip | To 12 inches (30.5 cm) lesssharply falcate; pointed ontip. |
| HEAD COLOR AND SHAPE | |
| Blunted and creased onfront; frequently allwhite in larger animals. | Uniformly brownish to graydistinctly bottlenosed. |
| MARKINGS | |
| Very often extensivelyscarred. | Less frequently scratchedand scarred. |
Distribution
Grampus are known to be distributed in temperate and tropical seas from at least eastern Newfoundland, south at least to St. Vincent, Lesser Antilles, and in the eastern and northern Gulf of Mexico. The species may not be as rare as the paucity of records suggests. Though they have been seen in Buzzards Bay on several occasions, grampus generally have an oceanic range and, along the Atlantic coast of North America, may be distributed from the Gulf Stream seaward, outside the theater of normal boating traffic.
Stranded Specimens
Stranded grampus are most readily identifiable by 1) the presence of only seven, or fewer, teeth in each side of the lower jaw (many of those teeth may have dropped out in older animals and remaining teeth may be extensively worn) and the absence of teeth in the upper jaw; 2) the presence of a distinct crease or bifurcation in the melon on the extreme front of the head; 3) the presence of numerous scratches and scars all over the body; and 4) the tall, slender, sharply falcate dorsal fin which may be more than 15 inches (38.1 cm) tall.
Figure 104.—Grampus off Fistler, Scotland ([top]) and from Baja California in the tank of Sea World, Inc., San Diego, Calif. ([bottom]). Note the tall pointed dorsal fin, which remains dark even in adult animals, the blunted head, which lacks a beak, and the extensive scarring of the body. In the photo on the right, note also the long pointed flippers and the white head characteristic of older animals. (Photos by A. S. Clark [top] and courtesy of D. K. Caldwell [bottom].)
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Medium-sized Whales Without a Dorsal Fin
BELUGA (T)
Delphinapterus leucas (Pallas 1776)
Other Common Names
White porpoise, white whale, belukha, sea canary, marsouin blanc (Quebec).
Description
Belugas reach a maximum overall length of about 16 feet (4.9 m). Males are slightly larger than females. In the western North Atlantic they have been found to grow to greatest lengths in oceanic environments near the southern extremities of their ranges, though they are found in far greater abundance in estuarine areas of the Arctic. Belugas have extremely robust bodies tapering to a distinct "neck" region and a very small head relative to body size.
They do not have a dorsal fin. Instead, along the back just behind the midpoint there is a narrow ridge notched laterally to form a series of small bumps. These ridges may be clearly visible on a swimming animal.
Newborn belugas are brown. As they age, they gradually lighten through slate gray, and by their sixth or seventh year have assumed the all-white coloration characteristic of adult animals.
Natural History Notes
Belugas feed on a variety of fishes (including cod and capelin), on squid, and on a variety of benthic crustaceans.
They are frequently found in shallow bays and river mouths, where the young are born, and occasionally ascend rivers.
May Be Confused With
Because of their limited distribution, all-white coloration and lack of a dorsal fin, belugas are unlikely to be confused with any other species of cetacean.
Distribution
Belugas have been reported from the Arctic Circle south as far as eastern Connecticut, typically in estuarine habitats, though they do range into oceanic regions. They are most abundant from the north shore of the Gulf of St. Lawrence northward. They remain near the Arctic Circle and in Hudson Bay to northern Greenland during winter, undertaking migrations to the south in autumn, straggling to the Maritime Provinces and as far as Connecticut. Belugas are regularly seen in the St. Lawrence and Saguenay rivers throughout late spring and summer. Return migrations to the north take place in spring.
A small population in the estuary of St. Lawrence is resident throughout the year.
Stranded Specimens
Stranded belugas are unlikely to be confused with any other species of cetaceans. The all-white coloration, the robust body shape with a rather small head and a distinct neck region, and the presence of 8-11 teeth in each of the upper jaws and 8-9 in each of the lower jaws permit positive identification.
NARWHAL (T)
Monodon monoceros Linnaeus 1758
Other Common Names
Unicorn whale (historical name not currently in use).
Description
The narwhal, also known as the unicorn whale because of the long tusk found on adult males, is one of two medium-sized whales found in the Arctic waters of the northwestern Atlantic. They reach a maximum length of from 15 to 16 feet (4.6 to 4.9 m) excluding the tusk. Newborn calves are approximately 5 feet (1.5 m) long. Narwhals have small rounded heads and a small mouth. Like the other medium-sized whale in the same region, the beluga or white whale, the narwhal has no dorsal fin. Instead, it has a series of bumps, approximately 2 inches (5.1 cm) high along the midline of the back in the half nearest the tail. The ridge created by these bumps may be readily seen on a swimming animal.
The basic coloration of the species changes slightly with age. Young animals are uniformly dark bluish gray on the back but rapidly begin to develop the numerous leopardlike spots on the back and sides characteristic of adults. Those spots rarely extend onto the belly even in old animals.
Narwhals have only two teeth. In the females, these teeth rarely emerge from the gums. In males, one and sometimes both of those teeth grow out the front of the snout, spiraling in a left-hand or sinistral direction, and may reach a length of 9 feet (2.7 m). One or two tusks may also be exposed, however, in females.
Natural History Notes
The function of the tusk in male narwhals is unknown, but it was this feature of the animal that earned it the name "unicorn whale" and resulted in its extensive hunting by whalers. During their annual migrations narwhals may congregate but are commonly found in groups of 10 or fewer during the rest of the year.
Narwhals feed on a variety of organisms, including cod, rockfish, flounder, and crabs, but their diet consists primarily of squid.
Distribution
Narwhals are found in the high arctic seas of the western North Atlantic, primarily in Lancaster Sound and its fringes. It has been noted that they are found in isolated pockets within that range and are not, like the beluga, widely distributed.
Narwhals make annual migrations in response to the movement of the ice. During the fall as the ice begins to form, the whales migrate to the south, sometimes reaching the Labrador coast. In the spring they return to the pack ice.
May Be Confused With
Narwhals are so different in coloration from the only medium-sized cetacean which shares its range and habitat—the beluga—that the two are highly unlikely to be confused. Belugas are usually all white or light slate gray in color, while narwhals are very much darker, ranging from bluish gray to brownish, and are often covered with light leopardlike spots. Furthermore, the body of the beluga is more robust.
Further, swimming narwhals frequently buck their heads up to breathe, a behavior which makes the tusk of adult males visible and permits positive identification.
Stranded Specimens
Stranded narwhals should be easily identifiable by the distinctive coloration and the unique characteristics of the teeth. In adults, one or two of the teeth may develop into the long, left-hand spiraling tusk, shown in Figures 112 and 114. Immature animals have no teeth which are emerged.
Small Whales, Dolphins, and Porpoises With a Dorsal Fin
ATLANTIC SPOTTED DOLPHIN (T)
Stenella plagiodon (Cope 1866)
Other Common Names
Spotter, Gulf Stream spotted dolphin, spotted porpoise, long-snouted dolphin.[11]
[11] See also p. 110. The common name "long-snouted dolphin" was once widely used for this species. It is now more frequently used for Stenella longirostris, also known as the spinner dolphin.
Description
Atlantic spotted dolphins reach a maximum adult length of 7.5, perhaps 8 feet (2.3 to 2.4 m). They are generally more robust in body shape than the other species of Stenella, closely resembling Atlantic bottlenosed dolphins in that regard, though the Atlantic spotted dolphins tend to be more slender.
The dorsal fin is distinctly back-curved and pointed on the tip, also closely resembling that of the Atlantic bottlenosed dolphin.
As the common name suggests, the Atlantic spotted dolphins are marked dorsally with numerous grayish-white spots on a darker background and ventrally with dark spots on a lighter background, though the extent of the spotting and the additional details of coloration change with age.
Immature animals lack spots completely. They are dark gray or purplish gray on the back, becoming lighter gray on the sides and white on the belly. The cape along the back is distinctly separated from the lighter gray coloration of the sides. The flippers and the trailing edge of the flukes are darker than the rest of the body.
As they age, the Atlantic spotted dolphins develop grayish-white spots, first low on the sides, spreading upward. During this stage, the cape becomes less distinct, and dark spotting begins to develop on the belly, the spots increasing in number with increasing age. In adult animals, the belly is often extensively covered with dark blotches but never becomes completely black. The lips may be white, and the beak is characteristically tipped with white, a feature which may aid in identification at sea.
The Atlantic spotted dolphins have a spinal blaze and a light line which extends from the flipper to the eye.
Natural History Notes
Little is known of the natural history of the Atlantic spotted dolphins. The species occurs in herds of up to several hundred individuals, though groups of 50 or fewer (6-10) are more common. They are often seen jumping clear of the water and habitually ride the bow wave of moving vessels. As they do, the distinct cape or band of purplish gray on the back of younger animals and the spotting pattern of older animals may be visible.
Atlantic spotted dolphins feed primarily on squid but may also take carangid fishes, small eels, herring, or anchovies.
May Be confused With
Atlantic spotted dolphins, particularly young animals, may be easily confused with Atlantic bottlenosed dolphins because of the similarities in color pattern and general body shape. However, the Atlantic spotted dolphins have considerable purplish gray in their background colors and the Atlantic bottlenosed dolphins are more dark gray to brownish gray. This along with considerable differences in the overall sizes of the two species should permit positive identification. In general, the key differences between spotted and bottlenosed dolphins are as follows:
| Atlantic Spotted Dolphin | Atlantic Bottlenosed Dolphin |
|---|---|
| MAXIMUM SIZE | |
| To 7.5-8 feet (2.3-2.4 m). | To 8-10 feet (2.4-3.1 m)inshore, to as much as 12 feet(3.7 m) offshore. |
| BODY COLOR | |
| Dark purplish gray on back;lighter gray on sides andbelly; body becomesincreasingly spotted with age. | Dark gray on back; lightergray on sides; white or pinkon belly (old animals mayhave a few spots on belly,but most are not spotted). |
| HEAD AND BEAK | |
| Head more slender; beaklonger; lips and top of snoutoften white. | Head robust; beak short;beak usually uniformly gray(older animals' beak may bewhite at tip). |
| NORMAL DISTRIBUTION | |
| Usually found more than 5miles offshore; most commoninside 100-fathom curve. | Usually more coastal, oftenascending rivers and enteringlagoonal and estuarineareas. |
Young Atlantic spotted dolphins are so similar in appearance to the Atlantic bottlenosed dolphins that the frequent reports of mixed schools of the two species are probably occasioned by groups of spotted dolphins which include some young, still unspotted animals.
Atlantic spotted dolphins might also be confused with bridled dolphins. The two can be most readily distinguished by the following characteristics:
| Atlantic Spotted Dolphin | Bridled Dolphin |
|---|---|
| BODY SHAPE | |
| Usually robust, often likethat of the Atlanticbottlenosed dolphin. | More slender, more likethat of the Atlantic stripeddolphin. |
| BODY COLOR | |
| Spotted; purplish gray onback; lighter gray on sidesand belly becomingincreasingly spotted with age.As animals becomes morespotted, cape become lessdistinct. Body has spinalblaze and light line fromflipper to eye. | Spotted; side of head lightgray; body has stripe fromflipper to corner of mouth,though the stripe tends tofade as spotting increases.Cape on top of head moredistinct that on Atlanticspotted dolphin. Body has nospinal blaze. |
At sea the Atlantic spotted dolphins may also be confused with rough-toothed dolphins (p. [135]).
Distribution
Atlantic spotted dolphins are a common species in the continental waters of the tropical and warm temperate western North Atlantic. Although they are far more abundant south of Cape Hatteras, they have been reported from the latitude of Cape May, N.J. (some fishermen claim to have seen them even further north) south through the Gulf of Mexico and the Caribbean to Venezuela. Atlantic spotted dolphins may be replaced around the West Indies by the bridled dolphin.
Within this range, the Atlantic spotted dolphins appear to be generally restricted to the waters outside the 100-fathom curve, most commonly more than 5 miles offshore. However, populations in the Gulf of Mexico move inshore in the late spring, and may approach close to shore during spring and summer.
Stranded Specimens
Stranded Atlantic spotted dolphins may be difficult to distinguish from bridled dolphins. If the color pattern is still clearly visible, the differences in coloration described above, particularly those of the head, and the presence or absence of a spinal blaze may be used. But since external appearance other than coloration are often very similar, specimens should be photographed from as many aspects as possible and the entire specimen or the roughed-out complete skeleton transported to a museum for preparation and examination. Tooth counts recorded for the two species to date are also very similar.
BRIDLED DOLPHIN (T)
Stenella frontalis (G. Cuvier 1829)
Other Common Names
Bridled spotted dolphin, Cuvier's dolphin, gamin (St. Vincent), bridled porpoise.
Description
Bridled dolphins, the second species of spotted dolphins in the western North Atlantic, reach an adult length of at least 7 feet (2.1 m). Like the other, the Atlantic spotted dolphin (p. [104]), bridled dolphins are characterized by light grayish-white spots on the dark dorsal portions of the body and dark spots on the light ventral surface. Other details of the coloration differ somewhat. Bridled dolphins are dark gray on the back, fading to lighter gray on the sides and belly. They lack the spinal blaze characteristic of Atlantic spotted dolphins. Except on the head, the border between the back and side colors is indistinct. On the head, the cape (the dark color of the top of the head) is distinct. In the light gray of the side of the head are the markings from which the species derives its common name, "bridled dolphin." These are a black circle around the eye with an extension to the junction (apex) of the rostrum and the melon (present in nearly all dolphins) and a broad black stripe from the origin of the flipper to the corner of the mouth. This mouth-to-flipper stripe tends to fade as spotting increases. Both the upper and lower lips are white or pinkish.
Natural History Notes
Virtually nothing is known of the natural history of bridled dolphins except that they have been observed in small herds of from 5 to 30 individuals and sometimes ride the bow wave of a vessel.
May Be Confused With
At sea, bridled dolphins may be confused with Atlantic spotted dolphins or spinner dolphins. Differences by which they may be distinguished from the first are tabularized on p. [105]. Differences between spinner and bridled dolphins permitting identification at sea are as follows:
| Bridled Dolphin | Spinner Dolphin |
|---|---|
| COLORATION | |
| Distinct cape on top of head;side of head light gray;distinct stripes from flippersto corner of mouth and fromdark circles around eye toapex of melon. | Dark gray on back; tan oryellowish tan on sides; whiteon belly. |
| BEAK | |
| Shorter and more slender; allblack; lips white. | Extremely long and slender;dark gray to black on top,white below; lips black. |
| DORSAL FIN | |
| Uniformly dark gray. | Often lighter gray in middle,dark around border. |
Distribution
Bridled dolphins occur in tropical and subtropical waters primarily near coastal areas and islands, but are best known from the West Indies. They have been reported from the Antilles, from Texas, and from Florida north to North Carolina. It has been speculated that this species replaces the Atlantic spotted dolphin around the West Indies.
Bridled dolphins have not yet been described from the South American coast.
Stranded Specimens
Bridled dolphins have from 29 to 34 teeth in each upper jaw and from 33 to 36 in each lower jaw. They can be distinguished from spinner dolphins, which have 46-65 teeth in each jaw, by this character alone.
They may be distinguished from spotted dolphins only if the color pattern of the head is clearly visible. If it has faded, the specimen will probably require museum preparation and examination before it can be positively identified.
SPINNER DOLPHIN (T)
Stenella longirostris Gray 1828
Other Common Names
Long-snouted dolphin, long-beaked porpoise, spinner porpoise, rollover (St. Vincent).
Description
Spinner dolphins reach a maximum length of about 7 feet (2.1 m). The body is slender. The beak varies from extremely long and slender (Fig. 123) to relatively short (Fig. 125); the beak is usually dark on top and clean white below, though there may be some white above. The tip of the snout and the lips are distinctly black, while those of both species of spotted dolphins are light. The back is dark gray to black, the sides are tan to yellowish brown, and the belly is white. Some of the larger animals appear almost all black with faint, light speckling. The dorsal fin is generally moderately falcate, but may be almost triangular in adult males. It is often a lighter gray near the middle, bordered by black or dark gray.
Natural History Notes
Spinner dolphins derive their common name from their habit of leaping clear of the water and spinning on their longitudinal axis. The reasons for this behavior are unknown. Individuals may rotate 2 times, or more, in one leap but spinning behavior is not observed as frequently in the western North Atlantic as it is in the eastern tropical Pacific.
Spinner dolphins occur in herds of up to several hundred individuals and are often seen jumping clear of the water, working the sea surface into a froth. They frequently come to the bow of a boat from considerable distances to ride in the bow wave and may ride for protracted periods.
May Be Confused With
Spinner dolphins may be confused with saddleback dolphins. Both species occur in large herds and often come to moving vessels to ride the bow wave. The two can be distinguished, however, by these differences:
| Spinner Dolphin | Saddleback Dolphin |
|---|---|
| COLORATION | |
| Dark gray on back; tan oryellowish tan on sides; whiteon belly; lacks crisscrosspattern on sides; distinctblack stripe from flipper toeye. | Dark gray to brownish grayon back; white on belly withcrisscross or hourglass patternof tan to yellow on sides;distinct black stripe fromflipper to middle of lowerjaw. |
Spinner dolphins might also be confused with bridled dolphins, but may be distinguished by the differences summarized on p. [108].
Distribution
Spinner dolphins are distributed in oceanic and coastal tropical waters. Though one specimen was collected from South Carolina, they have been more frequently reported from both coasts of Florida, the Gulf of Mexico, the Caribbean, and the West Indies. They have also been reported from Venezuela. They are said to be the most abundant dolphin species from the southeastern Caribbean. Some Pacific spinner dolphins are distributed in oceanic zones. Atlantic spinners may be abundant in offshore tropical waters as well.
Stranded Specimens
Stranded spinner dolphins are most readily identified by the extremely long rostrum and the 46-65 teeth, far more than any other species of dolphin. Note that the striped dolphins may have from 43 to 50 teeth per side in each jaw. However, striped dolphins are decidedly larger (to about 9 feet [2.7 m]), have a shorter beak, and are distinctly marked with dark stripes from the eye to the flipper, from the eye to the anus, and from the area behind the dorsal fin forward, towards but not reaching the head.
Saddleback dolphins also have from 40 to 50 teeth on each side but are also easily distinguishable by the differences in coloration discussed above for living animals at sea.
STRIPED DOLPHIN (T)
Stenella coeruleoalba (Meyen 1833)
Other Common Names
Euphrosyne dolphin (Stenella styx), Meyen's dolphin, blue-white dolphin, Gray's dolphin, striped porpoise, streaker porpoise.
Description
The striped dolphin is a widely distributed relative of the spinner and the Atlantic spotted dolphins, though it more closely resembles saddleback dolphins than either of these two species. It reaches a maximum length of about 9 feet (2.7 m) and is characterized by a series of distinctive black stripes. One band of black begins near the eye and extends down the side of the body to the area of the anus. (A small secondary stripe originating with this band turns off and disappears in the white coloration of the side just above the flippers.) A second band of black extends from the eye to the flipper. Some workers have contended that striped dolphins are separable into distinct species depending on whether the eye-to-flipper stripe has one (S. coeruleoalba) or two (S. styx) components.
Most individuals have an additional distinctive finger of black coloration which extends from the black coloration behind the dorsal fin forward towards and about halfway to the eye. It is this feature which is most distinctive in animals riding the bow or leaping clear of the water. The back is dark gray to bluish gray, the sides are lighter gray, and the belly is white.
Natural History Notes
Though little is known of this species, it has been reported in herds of up to several hundred individuals and apparently exhibits behaviors very similar to those of the saddleback dolphins (p. [116]), frequently jumping clear of the water. Atlantic and Mediterranean animals have been reported to bow ride.
May Be Confused With
This species is most likely to be confused with the saddleback dolphin, which it closely resembles. The two may be distinguished by the following characteristics:
| Striped Dolphin | Saddleback Dolphin |
|---|---|
| LENGTH | |
| To about 9 feet (2.7 m) ormore. | Seldom greater than 7.5 feet (2.3 m). |
| COLORATION | |
| Back from light gray to darkgray to bluish gray; sidesgray; belly gray or white;distinctive black lateralstripping from 1) eye toflipper, 2) eye to anus, and 3)dark color behind dorsal finforward, towards but notreaching head. | Back basically black orbrownish; distinct whitechest or belly patch;hourglass or crisscrosspattern on the sides;distinct black stripe fromflipper to middle of lowerjaw. |
Distribution
Striped dolphins are widely distributed in the temperate, subtropical, and tropical seas of the western North Atlantic. They have been reported from at least Halifax, Nova Scotia, south as far as Jamaica. (Additional records, purportedly from southern Greenland, involved a museum specimen. Since striped dolphins of the eastern North Atlantic are rare north of England, the species occurrence near Greenland would be highly improbable.) Individuals have recently been reported from the Gulf of Mexico.
Despite this wide distribution, striped dolphins appear to prefer warmer waters and are probably normally confined to the Gulf Stream or the waters off the continental slope. Individuals appearing to the north of the range seem to have ventured northward with fingers of warm water.
Stranded Specimens
Stranded striped dolphins should be readily identifiable by the highly distinctive patterns of lateral striping discussed above for living animals. If the color pattern has faded, they may still be identified by their size, larger than other dolphin species of similar appearance, and the relatively large number of teeth (43-50 per side in both upper and lower jaws). Only the spinner dolphin, much smaller in body length and having a much longer beak, has more teeth (46-65 per side in each jaw).
SADDLEBACK DOLPHIN (T)
Delphinus delphis Linnaeus 1758
Other Common Names
Saddleback porpoise, common dolphin, crisscross dolphin.
Description
Saddleback dolphins reach a maximum overall length of about 8.5 feet (2.6 m) though most individuals are less than 7.5 feet (2.3 m) long. Males are slightly larger than females of the same age.
The body shape varies slightly but usually closely resembles that of the striped dolphin (p. [113]). The dorsal fin varies from nearly triangular to distinctly falcate and is pointed on the tip. It is sometimes all black and sometimes black on the borders with a lighter grayish region of varying size near the middle.
The back is basically black or brownish black, but this coloration and the extent of the striping patterns that form the impression of a saddle and the degree of color distinction between the different zones are highly variable.
The chest and belly are cream white to white and are the most distinctive features from a distance. Up close, the sides will be seen to be distinctly marked with an hourglass or crisscross pattern of tan or yellowish tan. This crisscross pattern is diagnostic for the species.
The rostrum is intermediate in length and shape between that of the spinner and that of the striped dolphin and is often black with a white tip.
Natural History Notes
Saddleback dolphins are often seen in herds of a thousand or more and are often very active, many animals leaping clear of the water at any time. Like spinner dolphins, saddleback dolphins are active bow-riders and often come to the boat from considerable distances. Once on the bow they often ride for extended periods of time.
Saddleback dolphins feed on squid and on a variety of fishes, including anchovies, myctophids, and hake.
May Be Confused With
Saddleback dolphins might easily be confused with striped dolphins and must be examined closely to be distinguished from them. Primary differences apparent in encounters at sea are as follows:
| Saddleback Dolphin | Striped Dolphin |
|---|---|
| COLORATION | |
| Back basically black orbrownish; distinct whitechest or belly patch; hourglassor crisscross pattern onsides, some tan to yellowishtan; distinct black stripefrom flipper to middle oflower jaw. | Back from light gray to darkgray to bluish gray; sidesgray; belly gray or white;distinctive black lateralstriping from 1) eye toflipper, 2) eye to anus, and3) dark color behind dorsalfin forward, towards but notreaching head. |
| LENGTH | |
| To 7.5 feet, rarely to 8.5 feet(2.3-2.6 m). | To 9 feet (2.7 m). |
From a distance, saddleback dolphins might also be confused with spinner dolphins because of the habits of both species of congregating in large schools with much jumping and splashing. Both species ride the bow wave, and close examination should permit positive identification using the following characteristics:
| Saddleback Dolphin | Spinner Dolphin |
|---|---|
| COLORATION | |
| Dark gray to brownish grayon back; white on belly withcrisscross or hourglass patternof tan to yellowish tanon side; distinct black stripefrom flipper to middle oflower jaw. | Dark gray on back; tan oryellowish tan on sides; whiteon belly; lacks crisscrosspattern on sides; distinctblack stripe from flipper toeye. |
Distribution
Saddleback dolphins are widely distributed in the temperate, subtropical, and tropical waters of the western North Atlantic Ocean. They have been reported off Newfoundland, Iceland, Nova Scotia, and the coast of Massachusetts, south along the coast of North America to the Caribbean (West Indies and Jamaica), in the Gulf of Mexico, and from South American waters at least to Margarita Island, Venezuela.
The species' occurrence in the more northerly portions of this range during the summer and early fall months appears to coincide with the intrusion of warm waters into those areas. They are not uncommon off Nova Scotia in summer and fall and are casual members of the marine mammalian fauna of the remaining Maritime Provinces during that period.
In previous years, saddleback dolphins were not uncommonly encountered by collectors of Marineland of Florida working the northeast coast of Florida, but the species has been conspicuously absent since about 1960. Reasons for this apparent shift of range are unknown.
Stranded Specimens
Saddleback dolphins have from 40 to 50 small, sharply pointed teeth in each side of both the upper and lower jaws. These numbers overlap with only those of the striped and spinner dolphins (with 43-50 and 46-65, respectively). Saddleback dolphins should be readily distinguishable from both these species by the features outlined under the descriptions of living animals and distinguishable from the bridled dolphins by the distinctive markings on the head of the two species (see Figs. 121 and 134).
FRASER'S DOLPHIN (T)
Lagenodelphis hosei Fraser 1956
Other Common Names
Sarawak dolphin, Bornean dolphin, Fraser's porpoise.
Description
Fraser's dolphins reach an overall length of at least 8 feet (2.4 m). They are extremely short-beaked and have a pronounced dark stripe, similar to that found on the striped dolphin, extending from the rostrum to the area of the anus. They are robust in build and have rather small flippers and dorsal fin relative to body size. The dorsal fin is slender, falcate, and pointed on the tip. The body is gray on the back and white on the belly. The color of the side is dominated by the striping pattern. A cream-white band beginning high on the rostrum extends above and past the eye, continues towards the tail, and finally dissipates in the body color above the anus. Just below and parallel to this cream-white band is a black one extending from the area of the eye to the anus. A second cream-white band below and parallel to this dark strip separates the darker gray coloration of the side from the white coloration of the belly. The flippers are dark above and below.
Natural History Notes
The little that is known of the natural history and behavior of the species may be summarized as follows: Fraser's dolphins occur in groups of up to at least 500 animals and in the Pacific are occasionally seen with spotted dolphins (Stenella attenuata). From all accounts, they are not uncommon in certain areas of the tropical Pacific and off South Africa.
Fraser's dolphins appear to be deep divers. They are aggressive swimmers and, when they surface to breathe, often charge to the surface, creating a spray from their heads. They have also been reported leaping clear of the water.
May Be Confused With
Fraser's dolphin is intermediate in form between Lagenorhynchus and Delphinus delphis (thus the composite name Lagenodelphis). Because the species is apparently limited to tropical waters, however, and because of the prominent stripe on the side of the body, Fraser's dolphins are more likely to be confused with the striped dolphins (p. [113]). The two species can be distinguished at sea by several characteristics:
| Fraser's Dolphin | Striped Dolphin |
|---|---|
| COLORATION | |
| Single broad black stripefrom beak and eye back toarea of anus. | Color dominated by series ofstripes from: 1) eye to anus;2) eye to flipper, and 3)black behind dorsal finforward, towards but notreaching the head. |
| BEAK | |
| Extremely short and indistinct. | Longer, much more distinctive. |
| BODY SHAPE | |
| Robust, particularly in frontof dorsal fin. | Slenderer. |
| FLIPPERS | |
| Small, dark in color, andoriginating in light color ofsides. | Longer, sometimes lighteron upper surface; note stripefrom front of flippers to eye. |
| DORSAL FIN | |
| Small, slender, slightlyfalcate, and pointed on top. | Taller dorsal fin, broader atbase. |
Distribution
Although Fraser's dolphins have yet to be described for the western North Atlantic Ocean, they are included here as "possibles" because of the recent discovery that their range is far more extensive than previously known. Records to date have been limited to offshore tropical waters.
The species was first described in 1956 from the remains of a beach-washed specimen from Sarawak in the South China Sea. Since that time specimens have been collected from the eastern tropical Pacific, and others have stranded in such widely divergent localities as Australia, South Africa, and Japan. Recent summaries have added sighting records from the Central Pacific, near the Phoenix Island, from northwest of the Galapagos Islands, and from South African waters.
Stranded Specimens
Stranded Fraser's dolphins should be readily identifiable by 1) distinctive coloration of the body; 2) short, indistinctive beak; and 3) robust form. The only other species of small dolphins with beaks of similar length and general appearance are the Atlantic white-sided and white-beaked dolphins (p. 123 and 126); these dolphins, both with far more northerly ranges, have 30-40 and 22-28 teeth in each side of each jaw, respectively, while Fraser's dolphins have from 40 to 44 teeth in the upper jaw and from 39 to 44 in the lower jaw.
ATLANTIC WHITE-SIDED DOLPHIN (T)
Lagenorhynchus acutus (Gray 1828)
Other Common Names
Atlantic white-sided porpoise, jumper (Newfoundland).
Description
Atlantic white-sided dolphins reach about 9 feet (2.7 m) in maximum length and are robust in form with a small but distinct beak (less than 2 inches [5.1 cm] long).
The dorsal fin is tall, distinctly back curved, and pointed on the tip. The tail stock is extremely thick and does not narrow laterally until very near the tail flukes.
The back is distinctly black, the belly white. The sides have zones of gray, tan, and white.
The single most distinctive feature of Atlantic white-sided dolphins is an elongated oval zone of white and yellowish white along the sides from just below the dorsal fin to the area above the anus. These patches of lighter coloration, clearly demarcated from each other and from the surrounding coloration, are frequently visible simultaneously with the dorsal fin as the animals roll at the surface to breathe. Even alone this feature permits positive identification of the species. The dorsal fin is often part gray, part black. The beak is all black.
Natural History Notes
Atlantic white-sided dolphins are known to congregate in herds of perhaps a thousand animals, though smaller herds are far more common. The species is often wary of ships and does not ordinarily ride the bow wave. Like a number of other species, white-sided dolphins have been reported in association with Atlantic pilot whales.
May Be Confused With
At sea, Atlantic white-sided dolphins are most likely to be confused with the white-beaked dolphins, with which they overlap in distribution. Though they are very similar in general appearance, the two can be distinguished in the following ways:
| Atlantic White-Sided Dolphin | White-Beaked Dolphin |
|---|---|
| COLORATION | |
| Elongated band of yellowishwhite and white along side,visible behind and belowdorsal fin as animal rolls. | Two grayish areas—one infront, the other below andbehind dorsal fin, visible asanimal rolls. |
| BEAK | |
| All black. | Sometimes white in parts ofrange though western Atlanticanimals are usually dark. |
| MAXIMUM SIZE | |
| To 9 feet (2.7 m). | To 10 feet (3.1 m). |
| DORSAL FIN | |
| Often part black, part lightergray. | Uniformly dark. |
Distribution
Atlantic white-sided dolphins are distributed, primarily offshore, in the cool waters between the Gulf Stream and the Labrador Current. They have been observed from Hudson Canyon, off New York City, north to southern Greenland and perhaps Davis Straits. Their normal range shares a southern boundary with the white-beaked dolphin but does not extend as far to the north.
Stranded Specimens
In addition to the features described above for living animals at sea, stranded Atlantic white-sided dolphins can be distinguished from white-beaked dolphins by the following:
| Atlantic White-Sided Dolphin | White-Beaked Dolphin |
|---|---|
| NUMBER OF TEETH | |
| 30-40 per side per jaw,sometimes more in upper. | 22-28 per side per jaw; havelarger individual teeth—to 6mm in diameter. |
| FLIPPERS | |
| Lower portion of forwardmargin more curved. | Lower portion of forwardmargin less acutely curved. |
| VENTRAL COLOR | |
| White coloration of bellyextends high onto sides ofbody. | White coloration of bellyextends to lower jaw but notabove flippers on sides. |
| CAUDAL CRESTS | |
| Tail stock strongly compressedlaterally; taller, narrowsrapidly just in front of flukes. | Tail stock less laterallylcompressed, tapers moregently towards tail flukes. |
WHITE-BEAKED DOLPHIN (T)
Lagenorhynchus albirostris Gray 1846
Other Common Names
White-beaked porpoise, squidhound (Newfoundland).
Description
White-beaked dolphins reach a maximum overall length of about 10 feet (3.1 m). The body is robust in form with a tall, uniformly dark-gray dorsal fin, and a short but distinct beak which, as the common name implies, is often light gray to white above and below, at least in European waters. The beak of animals in the western Atlantic populations is less frequently white. The back and sides are basically dark gray to black, and the belly is white to light gray.
Swimming white-beaked dolphins can be most readily identified by the two areas of pale coloration on the sides, one in front of and another below and behind the dorsal fin. These areas are clearly visible from a ship or aircraft as the animals roll at the surface.
Natural History Notes
White-beaked dolphins may sometimes occur in herds of up to 1,500 individuals. Like their cousins, the Atlantic white-sided dolphins, they do not commonly ride the bow waves of vessels.
White-beaked dolphins feed on squid, octopus, cod, herring, capelin, and sometimes on benthic crustaceans.
May Be Confused With
In their northerly range white-beaked dolphins are likely to be confused with only the Atlantic white-sided dolphins. The most distinctive features of white-beaked dolphins are 1) the two areas of paleness described above, 2) the prominent, dark gray dorsal fin, and sometimes 3) the white beak. Other features by which the two species may be distinguished in the brief encounters typical at sea are tabularized on p. [127].
Distribution
White-beaked dolphins are the more northerly of the two species of Lagenorhynchus in the western North Atlantic. They are found from Cape Cod, Mass., north to western and southern Greenland and Davis Straits, though they are apparently far more numerous to the north of this range. They appear in Davis Straits in spring and summer and leave that area in autumn, sometimes as late as November, to move southward. They winter as far south as Cape Cod, where they are the common dolphin species in April, May, and June (sometimes to July). Their migrations are poorly known.
Stranded Specimens
Stranded white-beaked dolphins can be most readily distinguished from white-sided dolphins by the substantial differences in coloration and the differences in numbers of teeth.
| White-Beaked Dolphin | Atlantic White-Sided Dolphin |
|---|---|
| TEETH | |
| 22-28 per side per jaw. | 30-40 per side per jaw,sometimes more in upperjaw. |
| COLORATION | |
| Beak sometimes gray orwhite above and below; twopale areas visible on livinganimals not visible on strandedspecimens. | Beak all black; side markedwith elongated areas ofwhite with streaking patternsof yellow and tan. |
Additional characteristics by which the two species may be distinguished are summarized on p. [123].
ATLANTIC BOTTLENOSED DOLPHIN (T)
Tursiops truncatus (Montague 1821)
Other Common Names
Bottlenosed porpoise, gray porpoise, common porpoise.[12]
[12] See also p. [150] for use of this common name for another species, the harbor porpoise.
Description
Atlantic bottlenosed dolphins reach a maximum overall length of about 12 feet (3.7 m) and weigh in excess of 1,430 pounds (650 kg). They have relatively stubby snouts and dorsal fins, which are broad at the base, tall, and falcate. Coloration varies slightly, but individuals are usually dark gray on the back, lighter gray on the side, grading to white or pink on the belly. Old females may have spots on the belly. The dark coloration of the back often appears as a highly distinct cape, particularly on the head.
Natural History Notes
Atlantic bottlenosed dolphins often occur in groups of up to several hundred individuals which usually consist of aggregations of small groups of no more than a dozen animals each. They frequently associate with the Atlantic pilot whales and are frequently found accompanying the right and humpback whales travelling along the Atlantic coast of Florida.
Atlantic bottlenosed dolphins have catholic tastes, feeding on shrimp, eels, catfish, menhadden mullet, and miscellaneous trash fish, to mention only a few. They are frequently found near shrimp boats, feeding on fish stirred up by the trawls or on discarded trash fish.
They sometimes move in to ride the bow wave of a vessel, turning on their sides, sometimes spinning completely around on their longitudinal axis when doing so. Individuals may also turn their heads downward or to the side. They are often found close to shore, in bays and lagoons, and sometimes venture up the larger rivers. Some individuals, especially the larger animals, are found as far offshore as the edge of the continental shelf. Atlantic bottlenosed dolphins sometimes ride the surf. Individuals may jump clear of the water as high as 15-20 feet (4.6-6.1 m), a behavior on which aquarium shows have capitalized.
Members of this species are the dolphins most commonly maintained in captivity at zoos, aquariums, marine parks, and research institutions. For that reason, they are perhaps more familiar to the general public than any other species of porpoise, dolphin, or whale.
May Be Confused With
From at least Cape Hatteras southward, the range of the Atlantic bottlenosed dolphins distributed in inshore areas may overlap with that of Atlantic spotted dolphins, particularly during the spring and summer, when the Atlantic spotted dolphins move inshore. There the two species may be confused. The Atlantic bottlenosed dolphins and the Atlantic spotted dolphins can be distinguished, however, by the following characteristics:
| Atlantic Bottlenosed Dolphin | Atlantic Spotted Dolphin |
|---|---|
| MAXIMUM SIZE | |
| 8 feet to as much as 12 feet(2.4 to 3.7 m). | 7.5-8 feet (2.3-2.4 m). |
| COLORATION | |
| Not spotted (old females mayhave spots on belly); darkgray on back; light gray onsides; white or pink on belly. | Dark purplish gray on back;lighter gray on sides andbelly; body becomes increasinglyspotted with age. |
| HEAD AND BEAK | |
| Head robust; beak relativelyshort. | Head more slender; beaklonger. |
Some Atlantic bottlenosed dolphins are distributed well offshore as far as the edge of the continental shelf. Those individuals may be confused with either rough-toothed dolphins (p. [135]) or with grampus (p. [96]). They may be distinguished from rough-toothed dolphins by the following:
| Atlantic Bottlenosed Dolphin | Rough-Toothed Dolphin |
|---|---|
| BODY COLOR | |
| Dark gray on back; lightgray on side; white or pink onbelly. | Dark gray, almost purplishwith yellow spots; lighter onbelly. |
| SNOUT | |
| Relatively short and stubby,and clearly demarcated fromforehead; usually all gray;some older individuals havewhite-tipped snouts and/orwhite lips. | Long and slender; notclearly demarcated fromforehead; lower jaw and lipsspeckled white. |
Distinguishing differences between the Atlantic bottlenosed dolphins in offshore areas and grampus are tabularized on p. [96].
In northeastern South America the range of the Atlantic bottlenosed dolphin apparently overlaps with that of the Guiana dolphin, which, except for size, it closely resembles (see p. [132]).
Distribution
The Atlantic bottlenosed dolphins are widely distributed in the temperate and tropical waters of the western North best known from New England southward to Florida, westward in the Gulf of Mexico, and thence throughout the West Indies and Caribbean to Venezuela.
In the northern portion of that range, Atlantic bottlenosed dolphins are distributed offshore. In the southern portions of their range from at least North Carolina southward, the majority are found nearshore and often enter bays and lagoons, and sometimes venture up the larger rivers. Daily migrations in these areas may follow tidal flow.
In these same southerly areas some Atlantic bottlenosed dolphins are distributed as far offshore as the edge of the continental shelf.
Stranded Specimens
Within their range, stranded Atlantic bottlenosed dolphins should be readily identifiable by 1) the robust body, 2) relatively short beak, and 3) the 20-26 teeth in each upper jaw and 18-24 in each lower jaw.
GUIANA DOLPHIN (T)
Sotalia guianensis (P.-J. van Beneden 1864)
Other Common Names
None known.
Description
Guiana dolphins are the second smallest cetacean species in the western North Atlantic, reaching a maximum length of only about 5.6 feet (1.7 m).
Their body shape is very similar to that of the Atlantic bottlenosed dolphin, though the beak is less clearly demarcated from the forehead.
The rather prominent dorsal fin is nearly triangular, curving only slightly backwards near the tip.
Guiana dolphins are steel blue to dark brown on the back and white on the belly. There is sometimes a brownish band extending from the dark color of the back in front of the dorsal fin back towards but not reaching the anus.
Natural History Notes
Guiana dolphins are usually found in groups of fewer than 10 individuals.
May Be Confused With
Because of their limited range and specialized habitats, Guiana dolphins are unlikely to be confused with any other cetacean species except perhaps Atlantic bottlenosed dolphins (p. [128]). These two species can be distinguished by the following characteristics:
| Guiana Dolphins | Atlantic Bottlenosed Dolphins |
|---|---|
| SIZE | |
| To only 5.6 feet (1.7 m). | 8 to as much as 12 feet(2.4 to 3.7 m). |
| DORSAL FIN | |
| More nearly triangular; curvedonly slightly backwardsnear tip. | Broad-based, tall, andfalcate. |
| DISTRIBUTION | |
| Found in rivers and estuaries,extend into only veryshallow nearshore waters onlimited area of South Americancoast. | Sometimes found nearshoreand in bays, river mouths,and estuaries, but extendfarther offshore. |
Distribution
Guiana dolphins are found in Lake Maracaibo, in the rivers of Guyana, and in the nearshore coastal waters of the northeastern portion of the Guianas.
Stranded Specimens
In their very limited range, stranded Guiana dolphins can be readily identified by their extremely small size (to 5.6 feet [1.7 m]) and nearly triangular dorsal fin. Furthermore, in addition to the characteristics listed above distinguishing living Guiana dolphins from Atlantic bottlenosed dolphins, the species can be distinguished by differences in the numbers of teeth:
| Atlantic Bottlenosed Dolphins | Guiana Dolphins |
|---|---|
| TEETH | |
| 20-26 in each upper jaw;18-26 in each lower jaw. | 26-35 in each jaw; oftenragged in arrangement. |
ROUGH-TOOTHED DOLPHIN (T)
Steno bredanensis (G. Cuvier in Lesson 1828)
Other Common Names
Rough-toothed porpoise, goggle-eyed porpoise.
Description
Rough-toothed dolphins reach a length of at least 8 feet (2.4 m). The coloration of the rough-toothed dolphins is quite variable. Individuals are often dark gray to dark purplish gray on the back with pinkish-white blotches on the sides and belly. The flippers and flukes are dark and the belly is white. Individuals are frequently scarred with numerous white streaks.
The most distinctive characteristic of the rough-toothed dolphin is its beak, which is quite long and slender, may be white or pinkish white along both sides, including one or both lips and the tip of the snout, and is not separated from the forehead by the transverse groove present in other long-snouted dolphins. Because the forehead and the sides of the head slope smoothly into the rostrum, when this animal is seen from above or from the side, its entire head appears very long and nearly conical.
Natural History Notes
Rough-toothed dolphins occur in small groups of 50 animals or fewer and are usually found off the edge of the continental slope. They may ride the bow waves.
May Be Confused With
In their offshore habitat, rough-toothed dolphins are most likely to be confused with Atlantic spotted dolphins (p. 104) and with Atlantic bottlenosed dolphins (p. [128]). They may be distinguished from Atlantic spotted dolphins by the following:
| Rough-Toothed Dolphin | Atlantic Spotted Dolphin |
|---|---|
| SNOUTS | |
| Long and slender; not clearlydemarcated from forehead. | Moderate in length andclearly demarcated fromforehead. |
They may be distinguished from Atlantic bottlenosed dolphins by the characteristics tabularized on p. [128].
Even at a distance the blotched coloration of the side and the white coloration of the rostrum of rough-toothed dolphins may be visible. If closer examination is possible, the distinctive shape and coloration of the beak make positive identification easy.
Distribution
Though records of rough-toothed dolphins from the western North Atlantic are scant, the species is assumed to be widely distributed in deep tropical to warm temperate waters. It has been reported from Virginia, Georgia, Florida, the Gulf of Mexico, the West Indies, and off the northeastern coast of South America.
Stranded Specimens
In addition to the characteristics listed above for distinguishing living animals, stranded rough-toothed dolphins can be readily identified by the fact that the 20-27 fairly large teeth per jaw per side have a series of fine vertical wrinkles on the crown, a characteristic from which the species derives its common name. (These wrinkles are often difficult to detect.)
PYGMY KILLER WHALE (T)
Feresa attenuata Gray 1874
Other Common Names
Slender blackfish, slender pilot whale.
Description
Pygmy killer whales reach a length of about 8-9 feet (2.4-2.7 m). They are usually relatively slender-bodied with a rounded head, an underslung jaw, and no beak.
The falcate dorsal fin, located about the center of the back, is usually between 8 and 12 inches (20.3 and 30.1 cm) tall (though it may reach 15 inches [38 cm] in some individuals), is sometimes very distinctive, and resembles that of the Atlantic bottlenosed dolphin. The flippers are slightly rounded on the tips.
The color has been described as dark gray or black on the back, often lighter on the sides, extending higher in front of the dorsal fin and with a small zone of white on the underside, often a lighter gray area on the sides, and distinctive white regions around the lips. The chin may be completely white. This white zone on the chin, described as a "goatee," is often clearly visible in swimming animals.
May Be Confused With
The pygmy killer whale resembles the false killer whale but is much smaller and can be distinguished at close range by the zones of white coloration. False killer whales are almost all black and reach a length of up to at least 18 feet (5.5 m). Pygmy killer whales are dark gray on the back, often lighter on the sides, and show a region of white on the belly which may extend so high up onto the sides that it is visible on a swimming animal. Further, they reach only 8-9 feet (2.4-2.7 m).
Pygmy killer whales may also be confused with the similarly sized and colored many-toothed blackfish. So little is known of the two species' appearance and behavior at sea that it is doubtful that they can be successfully distinguished, though many-toothed blackfish apparently lack the white region often seen on the sides of pygmy killer whales. Further, pygmy killer whales have rounded flippers and smoothly tapered heads, while those of the many-toothed blackfish are pointed on the tip and more sharply pointed (often described as a parrot beak).
Distribution
Pygmy killer whales are probably distributed in the tropical and subtropical waters of the western North Atlantic. They have been reported from Texas, the Atlantic coast of Florida, and St. Vincent Island, Lesser Antilles. Records of the species from the other oceans of the world suggest that its distribution is limited to tropical and subtropical waters.
Stranded Specimens
Stranded pygmy killer whales can be clearly distinguished from both the false killer whale and the many-toothed blackfish. In addition to the differences discussed above, the following are key differences between the pygmy and false killer whales:
| Pygmy Killer Whale | False Killer Whale |
|---|---|
| TEETH | |
| 10-13 in each side of upperand lower jaws; lower teethsmaller. | 8-11 per jaw per side,prominent. |
| VENTRAL COLORATION | |
| White from anus to under tailstock, white may extend upsides. | Dark from anus to tail stock;lighter pale gray area forwardbetween flippers. |
| FLIPPERS | |
| Smoothly rounded. | Characteristic hump on forwardmargin. |
Pygmy killer whales can be distinguished from many-toothed blackfish on the basis of the second species' larger number of teeth. (Many-toothed blackfish have from 22 to 25 teeth in the upper jaw and from 21 to 24 in the lower jaw.)
Figure 152.—Pygmy killer whales at sea northwest of Hawaii ([top]) off the island of Oahu, Hawaii ([middle]), and from southeastern Florida in the tank at the Wometco Miami Seaquarium ([bottom]). When swimming rapidly, pygmy killer whales may closely resemble the much larger false killer whales. In addition to their much smaller size, rarely exceeding 9 feet (2.7 m), however, pygmy killer whales can be distinguished by their more rounded head, the white coloration of the lips and chin, and the white zone on the belly, sometimes extending up the sides. (Photos by S. Ohsumi [top]; J. Naughton, National Marine Fisheries Service and courtesy of E. Shallenberger, Sea Life Park [middle]; and courtesy of Wometco Miami Seaquarium [bottom].)
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![[middle]](#1666290077451005871_i_144b.jpg.id-2136794101905167396.wrap-0.html.html){kind=link}
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MANY-TOOTHED BLACKFISH (T)
Peponocephala electra (Gray 1846)
Other Common Names
Hawaiian blackfish, melon-headed whale.
Description
Many-toothed blackfish reach lengths of at least 9 feet (2.7 m) and are similar in body shape to the larger false killer whale and the similar-sized pygmy killer whale. The body is elongated and slim with a rather slim tail stock. In general, the head is shaped like that of the false killer whale but has a sharper appearance to the snout, sometimes described as a parrot-beak. The forehead is rounded, slightly overhanging the lower jaw, and has no beak. The dorsal fin is up to 10 inches (25.4 cm). It is probably very distinctive as the animals surface to breathe. Many-toothed blackfish are black on the back and slightly lighter on the belly. The areas around the anus and genitals and the lips are unpigmented. Many-toothed blackfish are presumably rare.
May Be Confused With
Many-toothed blackfish may be confused with either the false killer whale or the pygmy killer whale. They are considerably smaller than the false killer whale, have a slightly more pointed snout, and lack the prominent humplike forward margin on the flippers which is characteristic of the false killer whale.
They are approximately the same size as pygmy killer whales, but the white area around the genitals which extends up onto the side in pygmy killer whales may be lacking in many-toothed blackfish. This species has pointed flippers, while those of pygmy killer whales are rounded on the tips. Many-toothed blackfish also have a slightly more pointed snout. Otherwise, the two species are virtually indistinguishable in encounters at sea.
Distribution
Although many-toothed blackfish have not yet been reported in the western North Atlantic, they are included in this guide because of a record from the eastern tropical North Atlantic and the known tropical distribution in other areas.
Stranded Specimens
Stranded many-toothed blackfish can be distinguished from false killer and pygmy killer whales by the number of teeth alone. Many-toothed blackfish have more than 15 per side per jaw (usually 21-25); both other species have less than 15.
PYGMY SPERM WHALE (T)
Kogia breviceps (Blainville 1838)
Other Common Names
None known.
Description
Pygmy sperm whales reach a length of at least 11 feet (3.4 m). They are characterized by 1) an extremely robust body that rapidly tapers near the tail, 2) a squarish head, and 3) a narrow, underslung lower jaw which is located well behind the tip of the snout. Along the side of the head, in approximately the same position where gill slits would be located on a fish of comparable size, there is a crescent-shaped bracket mark, often called a false gill.
The flippers, which are smoothly curved on the forward margin and may reach a length of 18 inches (45.7 cm) or more on an adult specimen, are located well forward on the body, just below and behind the bracket mark.
The dorsal fin is very small, falcate, and located in the latter half of the back.
Though coloration can be described only from stranded specimens and a few encounters with living animals, pygmy sperm whales appear to be dark steel gray on the back, shading to a lighter gray on the sides, and gradually fading to a dull white on the belly. The outer surface of the flippers and the upper surface of the tail flukes are also steel gray.
Natural History Notes
From the few accounts, the following may be summarized about the behavior of pygmy sperm whales at sea: They reportedly usually rise slowly to the surface to breathe, produce a blow that is inconspicuous, and do not normally roll aggressively at the surface like most other species of small whales. They reportedly fold their flippers flat against their bodies when swimming. They have been reported to lie motionless in the water with the back of the head on the surface and the tail hanging loosely down in the water. (A similar behavior in sperm whales has made them a minor hazard to shipping, since it has resulted in some collisions with ships.) When they are startled in this posture, they may defecate, issuing a cloud of reddish brown to rust-colored fece. Beached pygmy sperm whales have also been observed to defecate a fine chocolate feces.
Pygmy sperm whales apparently feed primarily on squid, but do take fish as well.
May Be Confused With
In general, when they can be examined at close range, pygmy sperm whales are so distinctive that they are unlikely to be confused with any other species except perhaps the dwarf sperm whales. At a distance, they might be confused with small individuals of any of the beaked-whale species (p. [78]) that also have a relatively small, falcate dorsal fin located in the latter third of the back. Closer examination should permit easy separation, however, since the pygmy sperm whale has a blunted head, while the beaked whales, as the name implies, have elongated "dolphinlike" beaks and are considerably larger. At sea, pygmy sperm whales are most likely to be confused with their cousins the dwarf sperm whales (p. [148] and Fig. [160]). The two species can be distinguished as follows:
| Pygmy Sperm Whale | Dwarf Sperm Whale |
|---|---|
| MAXIMUM SIZE | |
| To 11 feet (3.4 m). | To 9 feet (2.7 m). |
| DORSAL FIN | |
| Small to 8 inches (20.3 cm),falcate; located in latter thirdof back. | Taller, more like that ofbottlenosed dolphins; locatednear the midpoint of theback. |
| COLORATION | |
| Both species are dark steel gray on the back, grading tolighter on the belly. | |
Distribution
Because they have been rarely observed at sea, normal ranges for this species are not known. Based on stranding records, however, the following can be stated. In the western North Atlantic, pygmy sperm whales have been found as far north as Sable Island, Halifax, Nova Scotia, as far south as Cuba, and as far west as Texas in the Gulf of Mexico. They are frequently found stranded along the Atlantic coast of Florida and throughout the eastern and northern Gulf of Mexico.
Stranded Specimens
Because of the distinctive characters of the genus, stranded pygmy and dwarf sperm whales are unlikely to be confused with any other species of cetacean, though the rather narrow underslung jaw and the blunted head may result in their casual dismissal by some beach walkers as stranded sharks. The two species of Kogia may be distinguished by the following:
| Pygmy Sperm Whale | Dwarf Sperm Whale |
|---|---|
| TEETH | |
| 12-16 (rarely 10-11) in lowerjaw are larger; no teeth inupper. | 8-11 (rarely 13) small andextremely sharp teeth inlower jaw; sometimes haveup to 3 teeth in each upperjaw. |
| THROAT | |
| No creases or grooves onthroat. | Several short irregular creasesor grooves on throat. |
Figure 160.—On the beach the two species of Kogia can be readily distinguished. The pygmy sperm whale, K. breviceps, ([top]) reaches a length of about 11 feet (3.4 m); its dorsal fin is a small nubbin located in the latter half of the back. The dwarf sperm whale, K. simus, ([bottom]) reaches only about 9 feet (2.7 m); its dorsal fin, much taller and more "dolphinlike" in appearance, is located near the middle of the back. Coloration of fresh specimens is probably similar for both species—the lightened areas in the lower photograph are the result of decomposition. (Photos from Jekyll Island, Ga. [top] and Atlantic Beach, Fla. [bottom] by D. K. Caldwell.)
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DWARF SPERM WHALE (T)
Kogia simus (Owen 1866)
Other Common Names
Rat porpoise (West Indies).
Description
Dwarf sperm whales reach an overall length of approximately 9 feet (2.7 m). Like the other species of Kogia, the pygmy sperm whale (p. [144]), the dwarf sperm whales are characterized by 1) a squarish head, 2) an extremely robust body which tapers rapidly near the tail stock, 3) a narrow, underslung lower jaw, and 4) a bracket mark or false gill on the side of the head.
The dorsal fin of this species is tall and falcate, closely resembling that of the Atlantic bottlenosed dolphin, and is located near the midpoint of the back. There are several short, irregular creases or grooves on the throat similar to those found on the sperm whale (see Figs. [60], [165]).
Dwarf sperm whales are dark steel gray on the back, grading to lighter gray on the sides, and fading to dull white on the belly.
May Be Confused With
Because of their tall, falcate dorsal fin, dwarf sperm whales may be confused at a distance with any of the small dolphin species. Their all-black or dark steel-gray coloration and the blunted head increase the likelihood that they can be confused with pygmy killer whales or many-toothed blackfish. They will have to be examined at close range before they can be distinguished.
Dwarf sperm whales may also be confused with pygmy sperm whales (p. [144] and [Fig. 160]). The two species can be differentiated by the characteristics tabularized on p. [144].
Distribution
Since it has only recently been recognized as a species distinct from the pygmy sperm whale and even more recently given a common name, records of dwarf sperm whales may have been confused with those of its close relatives. The dwarf sperm whale has been reported from at least Georgia south to St. Vincent, Lesser Antilles, and throughout the eastern and northern Gulf of Mexico. It is highly likely that this species, like the pygmy sperm whale, extends further to the north.
Stranded Specimens
Because of the distinctive characteristics of the genus, neither species of stranded Kogia is likely to be confused with any other species. They can be distinguished from one another by the characteristics tabularized on p. [144].
HARBOR PORPOISE (T)
Phocoena phocoena (Linnaeus 1758)
Other Common Names
Common porpoise, herring hog, puffing pig (Newfoundland and New England), Pourcils (Quebec), harbour porpoise.
Description
The harbor porpoise is the smallest cetacean species in the western North Atlantic Ocean, reaching a maximum overall length of about 5 feet (1.5 m). Its most distinctive identifying features in encounters at sea are 1) the small, chunky body; 2) the coloration, dark brown or gray on the back, fading to lighter grayish brown on the sides, often with speckling in the transition zone, and white on the belly extending farther up on the sides in front of the dorsal fin; 3) the small rounded head, lacking a distinctive beak; 4) the small, triangular dorsal fin; and 5) the shallow, inshore northerly distribution.
Natural History Notes
As the name implies, the harbor porpoise inhabits bays, harbors, river mouths, and all the relatively shallow inshore water between. Though it may travel in schools of nearly a hundred individuals, it is more often seen in pairs or in small groups of from 5 to 10 individuals. It often swims quietly at the surface. It will not ride the bow wave and is very difficult to approach closely by boat.
May Be Confused With
The harbor porpoise is not known to associate with dolphins but is sometimes seen in close proximity to fin whales and humpback whales off the Canadian coast in spring and summer. Because of its northern inshore habitat, the harbor porpoise is not likely to be confused with any other cetacean.
Distribution
Harbor porpoises are restricted to the colder waters of the western North Atlantic Ocean. They have been reported from North Carolina north to the Davis Straits and the waters of southwestern Greenland. Within this range they are probably most common in the Bay of Fundy and off southwest Greenland.
Stranded Specimens
In addition to the characteristics described above for living animals, stranded harbor porpoises can be readily identified by the small spade-shaped teeth, 22-28 per jaw.
ACKNOWLEDGMENTS
Obviously this guide could not have been produced without the cooperation of many people. Of over 450 individuals and scientific organizations contacted in 14 countries, 255 responded to our letters and well over 100 provided photographs for review and selection. We were particularly pleased that for the majority of the species found in the western North Atlantic our most difficult problem was narrowing the choices and ultimately selecting illustrations from the many good materials made available to us. Although there are far too many contributors to mention all by name, their prompt and enthusiastic responses to requests for help are gratefully acknowledged, whether or not their materials were used.
Although photo credits follow each figure, we would particularly like to cite the generosity of Marineland of Florida, Hideo Omura of the Japanese Whales Research Institute, J.G. Mead of the U.S. National Museum, K.C. Balcomb of Moclips Cetological Society, Seiji Ohsumi of the Far Seas Fisheries Research Laboratory, Jack Lentfer of the Alaskan Department of Fish and Game, the U.S. Naval Undersea Center (NUC), The University of Rhode Island, and William F. Perrin of the National Marine Fisheries Service (NMFS). Photographs by Taruski, McCann, Hain, Wheeler, and Rigley are in Winn's files. All others are in the files of Leatherwood and Caldwell. The illustrations for Figures B1 and D1 were prepared by George Galich of NUC. All other illustrations were prepared by Lois Winn.
The extensive and often tedious job of preparing black and white photographs of suitable format from the vast array of black and white and color negatives and prints and from color transparencies was accomplished at the NUC Photographic Laboratory by the able team of Domingo Sanchez, Ray Krenik, Jeanne Lucas, and Alan McPhee.
George E. Lingle and John C. Moore assisted with gathering and reviewing the literature and with cataloging and screening photo materials.
The various drafts of the manuscript were typed by Linda Thomson, Margaret Alvarez, and Sandra Nolan. Sandra Peterson assisted with proofreading the later drafts.
In preparing this guide we drew freely from the literature on cetaceans of this region and supplemented it with our own observations and with unpublished notes provided by our colleagues. A partial list of materials used, each a good source of reference material on cetaceans in general or on cetaceans of the western North Atlantic in particular, is provided in the following section, "Selected Bibliography."
All of the following colleagues read all or part of the manuscript and made useful suggestions for its improvement: K.C. Balcomb, W.C. Cummings, J.G. Mead, Hideo Omura, W.F. Perrin, F.K. Rodgers, Allen N. Saltzman, D.E. Sergeant, W.A. Watkins, A.A. Wolman, and F.G. Wood.
All of the information and photographs contributed by Lois Winn were obtained under grants from the Office of Naval Research. Funds and assistance for the preparation of intermediated drafts and logistics support for all stages of preparation of this guide were provided by Biological Systems, Inc., St. Augustine, Fla.
In addition to securing funds for the preparation and publication of this guide, Paul Sund, Platforms of Opportunity Program, NMFS, Tiburon, Calif., provided continuing help and criticism.
To these and to all who use this guide to further help knowledge about the cetaceans of the western North Atlantic, we are grateful.
SELECTED BIBLIOGRAPHY
ANDERSEN, H. T. (editor).
1969. The biology of marine mammals. Academic Press, N.Y., 511 p.
BURT, W. H.
1952. A field guide to the mammals. Houghton Mifflin Co., Boston, 200 p.
CALDWELL, D. K., and M. C. CALDWELL.
1973. Marine mammals of the eastern Gulf of Mexico. In J. I. Jones, R. E. Ring, M. O. Rinkel, and R. E. Smith (editors), A summary of knowledge of the eastern Gulf of Mexico, p. III-I-1—III-I-23. State Univ. Syst. Fla. Inst. Oceanogr., St. Petersburg, Fla.
CALDWELL, D. K., and F. B. GOLLEY.
1965. Marine mammals from the coast of Georgia to Cape Hatteras. J. Elisha Mitchell Sci. Soc. 81:24-32.
CALDWELL, D. K., H. NEUHAUSER, M. C. CALDWELL, and H. W. COOLIDGE.
1971. Recent records of marine mammals from the coasts of Georgia and South Carolina. Cetology 5:1-12.
FRASER, F. C.
1937. Whales and dolphins. In J. R. Norman and F. C. Fraser, Giant fishes, whales and dolphins, p. 201-349. Putnam and Sons, Lond. [There are several editions of this work, all with the same information.]
1966. Guide for the identification and reporting of stranded whales, dolphins and porpoises on the British coasts. Br. Mus. Nat. Hist., Lond., 34 p.
GOLLEY, F. B.
1966. South Carolina mammals. The Charleston Museum, Charleston, S.C., xiv + 181 p.
GUNTER, G.
1954. Mammals of the Gulf of Mexico. In P. S. Galtsoff (coordinator), Gulf of Mexico, its origin, waters, and marine life, p. 543-567. U.S. Fish Wildl. Serv., Fish. Bull. Vol. 55.
HALL, E. R., and K. R. KELSON.
1959. Order cetacea—cetaceans. In The mammals of North America, 2:806-840. Ronald Press, N.Y.
HERSHKOVITZ, P.
1966. Catalog of living whales. Bull. U.S. Natl. Mus. 246, 259 p.
KELLOGG, R.
1940. Whales, giants of the sea. Natl. Geogr. Mag. 77:35-90.
LAYNE, J. N.
1965. Observations on marine mammals in Florida waters. Bull. Fla. State Mus., Biol. Sci. 9:131-181.
LEATHERWOOD, S., W. E. EVANS, and D. W. RICE.
1972. The whales, dolphins, and porpoises of the eastern north Pacific. A guide to their identification in the water. Nav. Underseas Cent., Tech. Publ. 282, 175 p.
LOWERY, G. H., JR.
1974. The mammals of Louisiana and its adjacent waters. Louisiana State Univ. Press, Baton Rouge, 565 p.
MITCHELL, E. D.
1973. The status of the world's whales. Nat. Can. 2(4):9-25.
MOORE, J. C.
1953. Distribution of marine mammals to Florida waters. Am. Midl. Nat. 49:117-158.
NORRIS, K. S. (editor).
1966. Whales, dolphins, and porpoises. Univ. California Press, Berkeley, 789 p.
PALMER, R. S.
1954. The mammal guide. Doubleday and Co., N.Y., 384 p.
RICE, D. W.
1967. Cetaceans. In S. Anderson and J. K. Jones (editors), Recent mammals of the world; a synopsis of families, p. 291-324. The Ronald Press, N.Y.
RICE, D. W., and V. B. SCHEFFER.
1968. A list of the marine mammals of the world. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 579, 16 p.
RIDGEWAY, S. H. (editor).
1972. Mammals of the sea; biology and medicine. Charles C. Thomas, Springfield, Ill., xiii + 812 p.
SCHEVILL, W. E.
1974. The whale problem. Harvard Univ. Press, Cambridge, Mass., 297 p.
SERGEANT, D. E., and H. D. FISHER.
1957. The smaller Cetacea of eastern Canadian waters. J. Fish. Res. Board Can. 14:83-115.
SERGEANT, D. E., A. W. MANSFIELD, and B. BECK.
1970. Inshore records of Cetacea of eastern Canada, 1949-68. J. Fish. Res. Board Can. 27:1903-1915.
SLIJPER, E. J.
1962. Whales. Hutchinson and Co., Ltd., Lond., 475 p. [There is also an American edition.]
TOMILIN, A. G.
1967. Cetacea. Mammals of the U.S.S.R. and adjacent countries. Isr. Program Sci. Transl., Jerusalem, Vol. IX, 717 p. [A compilation of worldwide data, originally published in Russian.]
TOWNSEND, C. H.
1935. The distribution of certain whales as shown by logbook records of American whaleships. Zoologica (N.Y.) 19:1-50.
TRUE, F. W.
1889. Contributions to the natural history of the cetaceans, a review of the family Delphinidae. Bull. U.S. Natl. Mus. 36:1-192.
WALKER, E. P.
1964. Mammals of the world. The Johns Hopkins Press, Baltimore, p. 1083-1145. [Cetaceans. There is also a second, revised edition of this work, and a third, revised edition is planned.]
APPENDIX A
TAGS ON WHALES, DOLPHINS, AND PORPOISES
Field studies of cetaceans are very difficult. First, it is extremely hard to be positive that an individual or a group of animals is the same from one encounter to the next. This means that it is nearly impossible to determine, for example, whether herds of animals are resident in an area or only seasonal visitors. Without information of this kind, determinations vital to population management, such as sizes of populations and natural ranges, are impossible to make.
Secondly, as we frequently point out in this guide, individual cetaceans are usually visible to a surface observer only during the brief moments when they break the air-water interface to breathe. The majority of their vital activities (e.g., feeding, reproduction, communication, establishing and maintaining position within the herd, and defending against natural enemies) take place primarily below the surface, well out of view to a surface observer.
In recent years, in an attempt to overcome some of these problems, scientists have been placing markers on various species of cetaceans and monitoring their movements. The following brief summary of major methods of tagging cetaceans is provided to acquaint the reader with markers he may expect to see in the western North Atlantic.