Whales, Dolphins, and Porpoises of the Western North Atlantic Part 13

HEAD

Raised area around blowholes, Blunted, long, smooth.

k.n.o.bs on upper surface.

FLUKES

Often white underneath, Smooth, all black on rear concaved and scalloped on margin.

rear margin, deeply notched.

FLIPPERS

Extremely long (to one-third Short; all black.

of body), white and scalloped on leading edge.

DORSAL FIN (OR HUMP)

Triangular to falcate fin, Rounded hump, two-thirds including a step or hump in back on back followed by front of the dorsal fin; knuckles or crenulations.

smooth.

When they can be examined at close range, humpback whales can be easily distinguished from all other large whale species with a dorsal fin by the tuberosities or k.n.o.bs on the head, by the long white flippers scalloped on the leading edge, by the small distinctive dorsal fin, and by their distinctive tail flukes.

Distribution

In the western North Atlantic, humpback whales are widely distributed from north of Iceland, Dis...o...b..y and west of Greenland, south to Venezuela and around the tropical islands of the West Indies. They have been reported from the central and eastern Gulf of Mexico. Summer ranges extend at least from New England north to the pack ice, and feeding concentrations may be found in any portion of this region. During winter, humpback whales migrate southward to the shallow borderlands of Bermuda, to the Bahamas, and to the West Indies to calve and mate.

Stranded Specimens

The most distinctive features of stranded humpback whales are 1) the ventral grooves, 14-22 in number, very wide and extending to the navel; 2) the tuberosities of the snout and lower jaw, often the sites of numerous barnacle colonies; 3) the long flippers (to nearly a third of the total body length); and 4) the distinctive rounded projection near the tip of the lower jaw.

If these characteristics are not sufficiently clear, the species may be identifiable by the characteristics of the baleen plates (Table 2).

[Ill.u.s.tration: Figure 33.--Three views of blowing humpback whales. The blow of this species is usually less than 10 feet (3.1 m) tall, wider than it is high, and has been described as balloon-shaped. In the photo on the top, the wind has already begun to distort the blow. In the photo on the bottom, two separate columns are visible. All baleen whales have a bipart.i.te blowhole, and if an observer is directly behind or in front of either the right whale or the humpback whale under ideal wind conditions, the blows of these two species may appear as two distinct spouts. (_Photos from West Indies by H. E. Winn (top and middle) and from off St. Augustine, Fla. by D. K. Caldwell (bottom)._)]

[Ill.u.s.tration: Figure 34.--Head views of surfacing humpback whales. Note the rather broad rounded appearance of the top of the head and the small head ridge, which extends from just in front of the blowholes to near the tip of the snout. In humpback whales the single central head ridge characteristic of most balaenopterid species is replaced in prominence by a series of k.n.o.bs, some of which are oriented along the same line as the head ridge. On the animal in the inset photo note also the characteristic rounded projection below the tip of the lower jaw, heavily encrusted with barnacles. (_Photos from off St Augustine, Fla.

by D. K. Caldwell and from West Indies by H. E. Winn (inset)._)]

[Ill.u.s.tration: Figure 35.--A mother humpback whale with her newborn calf off the northern West Indies. Newborn humpback whales are from 12 to 15 feet (3.7 to 4.6 m) long and are colored like the adults. Note the mother's long white pectoral flipper, clearly visible below the surface.

(_Photo by H. E. Winn._)]

[Ill.u.s.tration: Figure 36.--Humpback whales fall back into the water after breaching. Note the long flippers, distinctly scalloped on the leading edge. In the animal on the top, note also the k.n.o.bs on the head, visible in profile, the cl.u.s.ter of barnacles located on the rounded projection below the tip of the lower jaw, and the throat grooves.

(_Photos off Baja California by K. C. Balcomb (top) and off Bermuda by C. Levenson (bottom)._)]

[Ill.u.s.tration: Figure 37.--Often, particularly on their tropical breeding grounds, humpback whales lie on their sides at the surface, the long white pectoral flipper in the air. Note the p.r.o.nounced scalloping on the leading edge. (_Photos near West Indies by C. McCann (top) and H.

E. Winn (bottom)._)]

[Ill.u.s.tration: Figure 38.--A series showing the extreme variability in dorsal fin shapes of humpback whales: (a) a small ridge, (b) slightly falcate, (c) triangular with a p.r.o.nounced hump, (d) slightly rounded, (e) distinctly rounded, and (f) taller and more distinctly falcate.

(_Photos from northern West Indies by H. E. Winn (a, c, e) and C. McCann (b); off Baja California by K. C. Balcomb (d); and off St. Augustine, Fla. by D. K. Caldwell (f)._)]

[Ill.u.s.tration: Figure 39.--The humpback whale is the only large whale species with a distinct dorsal fin which regularly raises its tail flukes when beginning a long dive. When it does so, the scalloped trailing edge is often visible (f, g, h). When the diving whale is seen from the rear, the varying degree of white coloration on the undersides of the flukes aids in identification (h). (_Photos from northern North Atlantic by K. C. Balcomb (a-f), from West Indies by C. McCann (g), and from off Ma.s.sachusetts by W. A. Watkins (h)._)]

[Ill.u.s.tration: Figure 40.--Detail of the head of a humpback whale harpooned off j.a.pan. Note the k.n.o.bs along the top of the head and on the lower jaw, the rounded projection near the tip of the lower jaw and the wide ventral grooves. The large ma.s.s of tissue to the left of the animal is its tongue. In the inset photo from a Canadian whaling station, note the baleen plates, less than 3 feet (0.9 m) long and dark olive green to black in color. (_Photos by j.a.panese Whales Research Inst.i.tute, courtesy of H. Omura; and J. G. Mead (inset)._)]

[Ill.u.s.tration: Figure 41.--A humpback whale on the deck of a whaling station in western Canada. All of the species' most distinctive characteristics are evident in this photograph: (1) the hump and the dorsal fin; (2) the k.n.o.bs on the top of the snout; and (3) the long flipper, with numerous barnacles attached to its leading edge. (_Photo by G. C. Pike, courtesy of I. MacAskie._)]

[Ill.u.s.tration: Figure 42.--North Atlantic humpback whales have from 14 to 20 broad, widely s.p.a.ced ventral grooves which extend about to the navel. Those grooves remain good diagnostic characters for considerable periods after the animal's death, as evidenced in the freshly killed specimen from Newfoundland (top) and the badly decomposed stranded animal from New Jersey (bottom). (_Photos from U.S. National Museum, courtesy of J. G. Mead._)]

Large Whales Without a Dorsal Fin

BOWHEAD WHALE (B)

_Balaena mysticetus_ Linnaeus 1758

Other Common Names

Greenland whale, Arctic right whale, great polar whale.

Description

Bowhead whales, so-called because of the high-arching jaws and the resultant contour of the head, reach a maximum length of about 65 feet (19.8 m). They are extremely robust in form.

When viewed from the side, some swimming bowhead whales show two characteristic curves to the back: the first extends from the tip of the snout to just behind the blowholes; the second, encompa.s.sing the entire back, begins just behind the head and extends all the way to the tail.

This character may be present only in adult animals and may be more p.r.o.nounced in males. Younger animals, particularly females, are often stubbier and somewhat barrel-shaped behind the head. In all animals the back is smooth, lacking even a trace of a dorsal fin.

The head of the bowhead whale is smooth, black, and without the bonnet and the "rock-garden," the colorful cl.u.s.ters of callosities characteristic of the black right whale. The blowholes are widely separated, and the blow emanating from them projects upward as two separate, distinct spouts. Though two separate columns sometimes may be visible under windless conditions in the blows of most mysticetes, this feature is exaggerated and is most characteristic in the bowhead and right whales.

Bowhead whales are black overall, except for a white "vest" of uneven coloration on the chin. Within that vest, near the sides of the white zone, there may be a series of grayish black to black spots, which on some animals have been likened to a string of beads. The vest is clearly visible when a surfacing animal is viewed from the front or the side or when the animals hang vertically in the water with the head on the surface and the tail flukes down, as they do during periods of early spring mating.

Natural History Notes

Bowhead whales are usually found singly or in groups of up to three animals, though fall concentrations may include up to 50 animals.

Bowhead whales sometimes breach, throwing most of the body clear of the surface and reentering with a resounding splash.

May Be Confused With

Bowhead whales are the only species of large whales found routinely in Arctic waters. Though other species, including some of the balaenopterid whales and the right whale, may venture north as far as the southern limits of the bowhead whale and beyond, they usually do so in the spring and summer, at a time when the bowhead whales are farther to the north.

Even if they are encountered together, bowhead whales can be distinguished from all the balaenopterid whales by the absence of a dorsal fin. Bowhead whales have neither a fin nor the slightest trace of a dorsal fin or ridge, while all the balaenopterids have a dorsal fin; and their back is extremely smooth, like that of the right whale. The bowhead and right whales may be readily distinguished from one another by the characters listed below for stranded specimens.