Whale Primer, with Special Attention to the California Gray Whale

by Theodore J. Walker

Whale Types

Porpoises and Dolphins

Whales are known technically as cetaceans (pronounced seh-TAY-shuns); so also are the various porpoises and dolphins which are mostly eaters of fish. These are certainly the most numerous of all the cetaceans, making up in numbers for their small size (6 to 8 feet). A few species range between 20 and 30 feet. Porpoises and dolphins congregate around schools of fish. Therefore fishermen are constantly on the lookout for a sight of them. Since not infrequently the porpoises break the surface of the water, leaping completely clear as if for a look around, they are not difficult to locate. Porpoises and dolphins can be seen most frequently in coastal waters where fish are most abundant. The porpoise and dolphin families contain a great many species and it is beyond the scope of this treatise to differentiate or name them all. However, these families include such unique forms as the killer whale, narwhal, white whale (or beluga as it is known to the Eskimos), and the pilot or black whale. Generally one associates cetaceans with the ocean, so it may come as a surprise to find that four dolphin species live in such major rivers as the Amazon, La Plata, Ganges, and the Yangtze.

In dolphins, the mouth protrudes beyond the head as a beak or snout, and in porpoises, the front of the head is blunt or gently rounded. It is impossible to avoid confusion if one uses common names to separate the various whales. Even though the word whale properly covers all the kinds, to some it connotes only the larger species. Such a distinction is wholly arbitrary, and cannot properly differentiate the natural groupings of whales to which zoologists have assigned technical names. It would be impossible to summarize the variety of common names which many of the species have acquired through the centuries. The only solution to this is to refer to the whales by the technical names which connote relationship. (For readers who desire this differentiation, a brief listing of the groups and representatives of each are provided in an [appendix].)

BALEEN WHALES

BLUE WHALE (SULPHUR-BOTTOM WHALE) FIN-BACK WHALE (COMMON RORQUAL) GREENLAND RIGHT WHALE (BOWHEAD WHALE) BLACK RIGHT WHALE SEI WHALE HUMP-BACKED WHALE (unlabelled in picture) CALIFORNIA GRAY WHALE LITTLE PIKED WHALE (LESSER RORQUAL) PYGMY RIGHT WHALE The Sperm Whale is given here for size comparison only.

TOOTHED WHALES

SPERM WHALE BOTTLE-NOSE WHALE KILLER WHALE PILOT WHALE (BLACKFISH) CUVIER’S BEAKED WHALE FALSE KILLER WHALE TRUE’S BEAKED WHALE NARWAL WHITE WHALE (BELUGA) PYGMY SPERM WHALE BOTTLE-NOSE DOLPHIN COMMON DOLPHIN COMMON PORPOISE

Squid Eaters

The bottlenose whales are nearly toothless, feeding on squid like their close relatives, the sperm whales. Porpoises and dolphins possess many sharp conical teeth on both the upper and lower jaws, although the narwhal which is related to them, breaks the rule by being toothless save for the tusklike canine of the male. In this instance either the right or left tooth elongates to produce an 8-foot spear. The other tooth does not break the gum, and this is the condition found in the female where both are rudimentary and not evident. The bottlenose whales have but a single pair of teeth in the lower jaw, and their relatives, the sperm whales, have 18-28 conical teeth per side on the lower jaw, and these when fully grown may be 8 inches in length. Pockets are provided in the toothless gum of the upper jaw to accommodate the teeth when the mouth is closed.

The decline in the number of teeth in the sperm and bottlenose whales is thought to be the elimination of structures which are no longer useful. Whereas a porpoise’s long mouth, bristling with sharp teeth, insures the hooking and retention of a slippery active fish, a small mouth with a few teeth is adequate to crush and slurp down the squid and the weak-swimming fishes of the abyssal depths.

The sperm whale is the largest of the squid feeders, reaching 60 feet. There is a diminutive counterpart, the pygmy sperm whale, which reaches 13 feet. It is exceedingly rare, whereas the sperm whale is abundant in temperate and tropical seas. The beaked whales complete the groups specialized for feeding on squid. Besides the modification of the mouth, all these whales are noted for their ability to dive to great depths where their food abounds. Not only can they dive to great depths, but they can stay submerged for long periods—up to an hour? Sperm whales have been found entangled in the submarine cables which were known to be on the bottom at a depth of 3,000 feet. It is clear that such feeding habits have opened up vast areas of the oceans to these species.

Filter Whales

The whalebone whales seem to have undertaken two different lines of specialization in feeding: The right whales developed an enormous head with a very large filter plate, whereas the rorquals are much more streamlined with a small filter plate. The ability of the latter to gather food is insured by the pleated throat. The right whales lack a dorsal fin and are decidedly less streamlined. The rorquals have a dorsal fin. There are two species which do not exactly fit in either group. The humpback whale appears to be like the rorquals in that it has a pleated throat and a suggestion of a fin. It is however, a very bulky slow swimming species. The California gray whale, apparently, is intermediate between the two groups and may be thought to be a survivor of the ancestral stock from which both groups differentiated. It has neither a pleated throat nor a fin. The gray whale, like the right whale, has been slow to recover from whaling. It is likely that the populations were never very large. Only the rorquals seem to have the numbers needed for large whaling operations.