Part 9

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 in Slender, gently tapering larger animals. mouth long.

SHAPE OF BODY

Robust. Long and slender.

DORSAL FIN

Broad-based and falcate. Slender, tall, falcate, and pointed on tip.

COLORATION

Black with gray saddle Mostly black with gray blaze sometimes evident behind of variable extent and dorsal fin and gray region intensity on belly between on chin and belly. flippers.

BEHAVIOR

Will not ride bow waves; May ride bow waves, often seldom breaches. "porpoises" and breaches.

RANGE

Temperate waters from at Temperate seas from at least least North Carolina north. Maryland 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 deg.N (Virginia coast) are Atlantic pilot whales and those living south of lat. 38 deg.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, To one-sixth body length, or or more. less.

NORMAL RANGE

From North Carolina north. From North Carolina south.

TEETH

8-11 per row. 7-9 per row.

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 Carolina Primarily North Carolina north. south.

FLIPPERS

To one-fifth body length, To less than one-sixth body or more. length.

TEETH 8-11 per row. 7-9 per row.

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:

ATLANTIC BOTTLENOSED GRAMPUS 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 light Dark gray on body; lighter gray; older animals dark gray on sides; white or pink with grayish regions on on belly; may appear brownish chest and belly; very in water. old animals white and scarred.

DORSAL FIN

To 15 inches (38.1 cm); To 12 inches (30.5 cm) less sharply falcate; pointed sharply falcate; pointed on on tip. tip.

HEAD COLOR AND SHAPE

Blunted and creased on Uniformly brownish to gray front; frequently all distinctly bottlenosed. white in larger animals.

MARKINGS

Very often extensively Less frequently scratched scarred. and 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.

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