, positive identification may require reference to the
sperm whale (p. 57), which, though the sperm whale has been classified
with species without dorsal fin, has a rather distinct dorsal hump,
particularly noticeable when the animal arches the back and tail to
begin a long dive.

[Illustration: Figure 8a.--Swimming, blowing, and diving characteristics
of blue, fin, sei, and Bryde's whales.]

[Illustration: Figure 8b.--Swimming, blowing, and diving characteristics
of humpback, bowhead, right, and sperm whales.]

(40-65 feet [12-20 m] maximum overall length)

Without a Dorsal Fin

There are three species of large whales without a dorsal fin in the
western North Atlantic Ocean. Two of these, the bowhead or Greenland
whale, and its more widely distributed close relative the right whale,
are baleen whales. The third, the sperm whale, is a toothed whale. The
first two have relatively smooth backs without even a trace of a dorsal
fin. The sperm whale has a humplike low, thick, dorsal ridge, which,
from certain views, particularly when the animal is humping up to begin
a dive, may be clearly visible and look like a fin. But because the
profile of that hump and the knuckles which follow it are often not very
prominent in this species, it has been classified with the finless big
whales.

All three species are characterized by very distinctive blows or spouts.
In both the bowhead and the right whales, the projection of the blow
upward from two widely separated blowholes assumes a very wide V-shape
with two distinct columns, which may be seen when the animals are viewed
from front or back. Though this character may be visible under ideal
conditions in many of the other baleen whales species as well, it is
exaggerated and uniformly distinct in the bowhead and right whales and
may be used as one of the primary key characters. In the sperm whale,
the blow emanates from a blowhole which is displaced to the left of the
head near the front and projects obliquely forward to the animal's left.
This blow seen under ideal conditions positively labels a large whale as
a sperm whale.

Remember, however, that wind conditions may affect the disposition and
duration of the blow of any species and that a single character alone is
seldom sufficient to permit positive identification.

[Sidenote: BOWHEAD WHALE

_Balaena mysticetus_

p. 49]

Body to 65 feet (19.8 m) long.[8]
Body dark; back smooth.
Chin and belly often white