Sperm whales travel long distances, following the migrations of their prey. The adult females and the calves usually confine their movements to the latitudes between 40°N and 40°S of the equator. The range of adult males extends N to the Bering Sea and S to Antarctica; they join the females and young in the tropics during the breeding season. There are fewer males than females, and the animals are polygamous. The single calf, born after a gestation period of 12 months, is 12 to 14 ft (3.6–4.2 m) long at birth. Sperm whales feed chiefly on squid, octopus, and cuttlefish. Sperm whales are among the most aggressive of whales; they battle 30-ft (9-m) giant squid to the death and have been known, when attacked, to sink a rowboat full of whalers. They are thought to live 80 to 100 years.
A gray, cheeselike substance called ambergris, valuable as a perfume fixative, forms in the whale's intestine around the irritating, undigested beaks of squids. It is often expelled by vomiting and floats in chunks on the water. The head of the sperm whale may contain up to a ton of fine oil, known as sperm oil, and a wax called spermaceti. Sperm whaling was the foundation of the economic expansion of New England in the 18th cent. The industries founded on ambergris, sperm oil, and spermaceti resulted in the slaughter of sperm whales almost to extinction. With the decline in and then the moratorium on the hunting of this species, sperm whales have increased in numbers.
The pygmy sperm whale, Kogia breviceps, of the same family, is similar to the cachalot in range and feeding habits. It is 9 to 11 ft (2.7–3.4 m) long, bluish gray above shading to a dull white below, with a sickle-shaped dorsal fin. The largely similar dwarf sperm whale, K. sima, is 7 to 9 ft (2.1–2.7 m) long and has a more prominent dorsal fin. Because of the similarity in appearance and habit between the pygmy and dwarf sperm whales, the latter was not identified as a separate species until 1966.
Sperm whales are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Cetacea, family Physeteridae.
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