The sperm whale is the largest toothed mammal in the world. It is also the whale species that displays the greatest difference between the sexes. Males can attain weights of up to 50 t ( 55 tn.), while females weigh about one-third as much.

Sperm whales range across most of the world's oceans, but they are most usually found in those latitudes inhabited by the giant squid, which is its favourite food: off the coasts of South America, Africa, the Arabian Sea, between Australia and New Zealand, and all along the equator. Sperm whales will sometimes descend to depths of 900 m (3,000 ft.) in search of these creatures, which themselves measure more than 9 m (30 ft.) long. In addition to squid, these huge animals also take seals, rays and sometimes sharks up to 3.5 m (12 ft.) long.

Sperm whales have no teeth in the upper jaw. There are about 60 in the lower jaw, and these are about 20 cm (8 in.) long and usually weigh approximately 3 kg (6 or 7 lb.) each. The sperm whale's enemies are humans and killer whales.