Sperm whales usually are dark brownish gray in color. The body has a "corrugated" or "shriveled" appearance. The belly and the front of the head may be grayish to off-white. The skin around the mouth, particularly near the corners, is white. The undersides of the flukes and flippers vary in color through numerous shades of browns and brownish grays.
Natural History Notes
Sperm whales may dive to depths in excess of 3,270 feet (996.7 m) for periods of an hour or more. As do most whales upon surfacing from a deep dive, sperm whales emit a single explosive blow and then, depending on the length of the dive, may remain on the surface for over 10 min and blow more than 50 times before beginning the next dive. Shorter periods on the surface and fewer blows are more common. Females may dive and remain on the surface for shorter periods of time than males. When beginning a deep dive, sperm whales throw their broad triangular flukes, dark on the undersides, high into the air.
Sperm whales may be found singly or in groups of up to 35 or 40 individuals. Older males are usually solitary except during the breeding season. During the remainder of the year large groups may be bachelor bulls (sexually inactive males) or nursery schools containing females and juveniles of both sexes. Sperm whales are seldom found in less than 600 feet (182.9 m) of water.
Sperm whales feed primarily on squid but may occasionally also take octopuses and a variety of fishes.
May Be Confused With
Because of their distinctive head shape and blow, sperm whales are unlikely to be confused with any other species when they can be closely examined. If only the back and tail flukes are seen, however, sperm whales may somewhat resemble humpback whales. Both species arch the back when beginning a dive, raising the fin or hump, and both throw the tail flukes. The most distinctive differences between the two species are tabularized on p. [40].
At sea the head of a sperm whale may also somewhat resemble that of an adult male northern bottlenosed whale, but this latter species is lighter brown in color, has a distinct beak and a prominent dorsal fin, and is rarely found south of lat. 42°N. In addition, the blowhole of the northern bottlenosed whale is located well back on the head and not—as in the sperm whale—on the front.
Distribution
Sperm whales are widely distributed in oceanic areas of the western North Atlantic. They may be encountered from Venezuela north at least as far as the Davis Straits, though they apparently avoid the polar ice fields. Distribution and migrations vary between males and females. Males range farther to the north, while females and immature males remain between lat. 30° and 50°N. Both groups shift northward during spring and summer and return to southern portions of their range in the fall. Adult males arrive off the New England coast in August. Those reaching the Newfoundland and Labrador coasts arrive from the deep sea, perhaps following the slope contours, in August and September. Males are abundant as far north as southeast Greenland and Iceland in summer. Some animals remain as late as November, but the majority migrate south to temperate or tropical waters in the early fall.