Part 8

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 (p. 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.

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, All black with some gray on flank, and head. belly.

DORSAL FIN

Very tall and erect in adult Shorter, slender, strongly males; tall and slightly back falcate. curved in female.

HEAD SHAPE

Broad, rounded. Tapered, slender.

FLIPPER SHAPE

Paddle-shaped. Moderately long with characteristic hump near middle 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.

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.