sperm whale

(Physeter catodon), an aquatic mammal of the suborder Odontoceti.

The length of the male sperm whale reaches 20 m; it may weigh as much as 70 tons. The females are as long as 15 m and weigh up to 30 tons. The head is very large (as much as one-third the length of the body), massive, and blunt in the front. The left nostril opens at the end of the snout in the left corner of the head; the right nostril ends blindly. In the frontal part of the head there is a saccular enlargement of the right nasal passage—the air sac, an adaptation to prolonged stays under water. An enormous fatty cushion of spermaceti (to 6 m) lies in the bed formed by the maxillary bones and determines the shape and size of the head. The mouth is located below this area, a considerable distance back from the tip of the snout. There are 18-30 pairs of teeth on the long and narrow lower jaw. Upper teeth are absent. The flippers are broad and blunt; the dorsal fin takes the form of an elongated hump. The skin on the sides of the body and back is usually wrinkled. The color of the whale varies from brown to dark chestnut. The males are found in all oceans and open seas except in the arctic; the females, only in the warm zone between 40° S lat. and 40° N lat.

The sperm whale feeds on cephalopods and deepwater fish, descending as far as 1.2 km. It can stay under water as long as 1.5 hours, facilitated by the high myoglobin content of the muscles and the decreased sensitivity of the respiratory center to the accumulation of carbon dioxide in the blood. The sperm whale is polygamous, 10-20 females being escorted by a single male. Sexual maturity is attained at five years. The life span may be as much as 50 years. The sperm whale is a most important object of commerce, yielding 9-10 tons of fat, as much as 6 tons of spermaceti, and ambergris. The sperm whale population is decreasing (no more than 300, 000 remain).