Whales, Dolphins, and Porpoises of the Western North Atlantic Part 20

[Ill.u.s.tration: Figure 85.--A dense-beaked whale stranded in northeastern Florida. This species reaches about 17 feet (5.2 m) and is black or charcoal gray on the back, lighter gray on the sides, and frequently marked with grayish-white blotches and often extensively scarred.

(_Photo by W. A. Huck, courtesy of Marineland of Florida._)]

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 p.r.o.nounced 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 offsh.o.r.e waters from the lat.i.tude 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.

[Ill.u.s.tration: Figure 86.--North Sea beaked whales are the most northerly of the beaked whale species, extending north as far as the pack ice. They reach at least 16.5 feet (5.0 m) and can be identified on the beach by the position of the teeth near the middle of the lower jaw.

Little is known of the species at sea. (_Drawing by L. Winn._)]

[Ill.u.s.tration: Figure 87.--A female North Sea beaked whale (16.5 feet [5.0 m]) stranded in Hjertuika in 1957. (_Photo courtesy of A.

Jonsgard._)]

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 a.n.a.l 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. Doc.u.mented 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