nguished from each other on
the basis of differences in 1) the size, shape, and position of the
dorsal fin and the timing of its appearance on the surface relative to
the animal's blow (in general, the larger the whale, the smaller the
dorsal fin--the further back its position and the later its appearance
on the surface after the animal's blow); 2) the height of body in the
area of the dorsal fin, relative to the size of the dorsal fin, which is
exposed as the animal sounds; 3) sometimes the blow rate and movement
patterns; and 4) the shape and color of the head.

Despite variability in behavior by members of the same species from one
encounter to the next, an observer can greatly increase the reliability
of his identification by forming the habit of working systematically
through a set of characteristics for the species rather than depending
on any single characteristic.

[Sidenote: BLUE WHALE

_Balaenoptera musculus_

p. 19]

Body very large, up to 85 feet (25.9 m) long.[7]
Body basically bluish with mottlings of grayish white.
Baleen all black.
Head broad and nearly U-shaped, viewed from above.
Head flat in front of blowhole, viewed from side.
Dorsal fin small (to 13 inches [33 cm]), triangular to moderately
falcate, in the last one-third of back.
Distribution primarily from temperate seas to pack ice; rare in
tropics.
Distribution more northerly during summer.
Flukes occasionally raised slightly on long dive.

[Footnote 7: These figures are all near maximum sizes recorded for the
North Atlantic. For all species which have historically been exploited
by whale fisheries present maximum sizes may be significantly less than
these figures.

It should also be noted that differences in methods of measurements
often account for discrepancies in reported lengths.]

[Sidenote: FIN WHALE

_Balaenoptera physalus_

p. 26]

Body large, up to 79 feet (24 m) long.
Body mostly dark gray or brownish gray; undersides of flukes and
flippers and belly white; grayish-white chevron frequently on
back behind head.
Right lower lip white; right upper lip sometimes white; left lip
dark.
Head V-shaped, viewed from above.
Right front one-third to one-fifth of baleen plates, yellowish
white.
Other baleen bluish gray with yellowish-white stripes.
Dorsal fin to 24 inches (61 cm), slightly more than one-third
forward from tail; forms angle of less than 40 deg. with ba