(13-16 feet [4-5 m] maximum overall length)

Without a Dorsal Fin

The only two species of medium-sized cetaceans in the western North Atlantic which have no dorsal fin, the Beluga or white whale and the Narwhal, share such limited common range, well outside the theater of normal boating traffic, that they are generally infrequently encountered.

Both species are easily identifiable when seen.

Beluga
Delphinapterus leucas
p. [99]

Body to 16 feet (4.9 m) long.
Body of adults all white; young slate gray.
Small row of bumps along back ridge near midpoint, sometimes dark brown.
Distribution usually near coast from Arctic waters to St. Lawrence Gulf and into Hudson Bay.

Narwhal
Monodon monoceros
p. [102]

Body to 16 feet (4.9 m) long.
Body of adult brownish with grayish spots; body of young dark bluish gray fading to white belly.
Head small; adults may have tusks up to 9 feet long (2.7 m).
Small row of bumps along back ridge.
Distribution usually in coastal waters from Arctic waters south to Labrador coast.

SMALL WHALES, DOLPHINS, AND PORPOISES
(less than 13 feet [4 m] maximum overall length)

With a Dorsal Fin

The species in this group are not discussed in order of length; instead the species of the genus Stenella are treated together and then they and other species are placed in near proximity to those animals with which they are likely to be confused in the field.

Atlantic spotted dolphin
Stenella plagiodon
p. [104]

Body to 7.5-8 feet (2.3-2.4 m) long.
Body dark purplish gray on back, lighter gray on sides and belly; becomes increasingly spotted with increase in size.
Body has spinal blaze and light line from flipper to eye.
Beak white on tip.
Rides bow waves.
Distribution usually in tropical and warm temperate waters; most common inside 100-fathom curve of continents.

Bridled dolphin
Stenella frontalis
p. [108]

Body to at least 7 feet (2.1 m) long.
Body dark gray on back; lighter gray on sides and belly.
Body has no spinal blaze.
Cape on top of head distinct.
Bridle: dark lines from eye to rostrum and from flippers to corner of mouth.
Rides bow waves.
Distribution in tropical waters, primarily in West Indies.

Spinner dolphin
Stenella longirostris
p. [110]

Body to at least 7 feet (2.1 m) long.
Body dark gray on back; tan on sides; white on belly.
Beak often long and slender, usually black above, white below.
Tip of snout and lips distinctly black.
Dorsal fin moderately falcate to triangular and very erect.
Rides bow waves.
Often jumps and spins on longitudinal axis.
Distribution in oceanic and coastal tropical waters.

Striped dolphin
Stenella coeruleoalba = Stenella styx
p. [113]

Body to about 9 feet (2.7 m) long.
Body dark gray or bluish gray on back; gray on sides; gray or white on belly.
Distinctive black stripes from: 1) eye to anus, 2) eye to flipper.
Distinctive black blaze from behind dorsal fin to side above flipper.
Rides bow waves.
Distribution temperate, subtropical, and tropical; seldom close to shore.

Saddleback dolphin
Delphinus delphis
p. [116]

Body to 8.5 feet (2.6 m); usually less than 7.5 feet (2.3 m) long.
Body brownish gray to black; belly and chest white; crisscross (hourglass) pattern of yellow tan on sides.
Distinct black stripe from center of lower jaw to flipper.
Rides bow waves.
Distribution temperate and tropical; seldom close to shore.

Fraser's dolphin
Lagenoldelphis hosei
p. [120]

Body to at least 8 feet (2.4 m) long.
Body very robust in front of dorsal fin, resembling cross between saddleback dolphin and Atlantic white-sided dolphin.
Beak very short and indistinct.
Distinct black stripe from beak to area of anus.
Dorsal fin and flippers small.
Distribution tropical (not yet recorded in western North Atlantic).

Atlantic white-sided dolphin
Lagenorhynchus acutus
p. [123]

Body to about 9 feet (2.7 m) long.
Dorsal fin part gray, part black; tall and distinctly falcate.
Distinctive patch of white on side; tan or yellow coloration below and behind dorsal fin, often visible on swimming animal.
Beak short; all dark.
Does not usually ride bow waves.
Distribution Cape Cod to southern Greenland.

White-beaked dolphin
Lagenorhynchus albirostris
p. [126]

Body to about 10 feet (3.1 m) long.
Dorsal fin all black, tall, and distinctly falcate.
Two pale areas: one in front, another behind and below dorsal fin; visible on swimming animal.
Beak short, sometimes brushed with white blaze.
May ride bow waves.
Distribution Newfoundland north in summer, Cape Cod north in winter; common close to shore at Cape Cod in spring.

Atlantic bottlenosed dolphin
Tursiops truncatus
p. [128]

Body to 12 feet (3.7 m) long.
Body dark gray on back; lighter gray on sides; belly white to pink.
Snout robust and short.
Dorsal fin tall; back curved.
Ride bow waves; often turn head downwards or to the sides as they do so.
Distribution temperate and tropical, usually within 20 miles of shore (often in bays, lagoons, and larger rivers) but extending off the continental shelves.

Guiana dolphin
Sotalia guianensis
p. [132]

Body to approximately 5.6 feet (1.7 m) long.
Body steel blue to dark brown on back; white on belly.
Dorsal fin nearly triangular; curves only slightly backward.
Distribution in Lake Maracaibo and the rivers of Guiana and in the nearshore coastal waters of northeastern portion of South America.

Rough-toothed dolphin
Steno bredanensis
p. [135]

Body to about 8 feet (2.4 m) long.
Body dark gray to purplish gray on back with white or pink blotches on sides; belly white.
Body frequently shows numerous white scars.
Head tapers gradually; beak long and slender; no clear separation of beak from forehead.
May ride bow waves.
Distribution in deep tropical waters.

Pygmy killer whale
Feresa attenuata
p. [138]

Body to 8-9 feet (2.4-2.7 m) long.
Body black with white belly patch which may extend up sides in area of anus.
Head rounded; no beak; lips white; lower jaw and chin may be white.
Dorsal fin to 15 inches (38 cm) tall, falcate; located near midpoint of back.
Distribution tropical and subtropical.

Many-toothed blackfish
Peponocephala electra
p. [142]

Body to about 9 feet (2.7 m) long.
Body black on back; light gray on belly.
Head rounded; no beak; underslung jaw; lips white.
Dorsal fin to 10 inches (25.4 cm), tall, distinctly back curved.
Distribution tropical (not yet reported in western North Atlantic).

Pygmy sperm whale
Kogia breviceps
p. [144]

Body to about 11 feet (3.4 m) long.
Body dark steel gray on back; lighter gray on sides; pinkish to white on belly (older animals speckled on belly).
Head blunt; jaw underslung; false gills or bracket marks on side of head.
Dorsal fin small; located in last one-third of body.
Has not been reported to ride bow waves.
Distribution in tropical and temperate waters.

Dwarf sperm whale
Kogia simus
p. [148]

Body to about 9 feet (2.7 m) long.
Body dark steel gray on back; lighter gray on sides; pinkish to white on belly.
Head blunt; jaw underslung; false gills or bracket marks on side of head.
Body has two small creases on throat.
Dorsal fin like that of Atlantic bottlenosed dolphin; located near midpoint of back.
Has not been reported to ride bow waves.
Distribution poorly known; at least from Georgia to the tropical seas.

Harbor porpoise
Phocoena phocoena
p. [150]

Body to 5 feet (1.5 m) long.
Body dark brown above and white below; transition zone on sides often speckled or streaked; ventral white extends high onto side in front of dorsal fin.
Head rounded; beak small and indistinct.
Dorsal fin short and triangular.
Distribution in shallow waters from at least Delaware north; generally found inshore; often in bays, river mouths and inlets.
Does not approach boats.