"Sperm whales can dive deeper than 1.6 km and stay under for 90 minutes, although shorter, shallower dives are more usual. They eat squid and octopus, which are sucked into the mouth whole. The whale's head is huge. In addition to containing a very large brain, it houses the wax-filled spermaceti organ. Scientists are still trying to learn what this organ does. It might help absorb excess nitrogen during dives, or help buoyancy. A third possibility is that it helps in communication. Sperm whales make intense clicking sounds - presumably to communicate - and the spermaceti organ might help the sounds resonate. Sperm whales are found in breeding schools and bachelor schools. Breeding schools consist of about 20-40 mature females and juveniles of both sexes, accompanied by one or more mature males. Up to 50 males are found in bachelor groups. Females are sexually mature at 7-13 years, and males at 18-21 years. Pregnancy lasts 14 or 15 months, and females calve only every 3-6 years. So large, so slow to reproduce, and once heavily hunted for their spermaceti, blubber, and ambergris, which forms in the intestines and was used in the perfume industry, sperm whales are now vulnerable. Since 1986, there has been a moratorium on hunting them."

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Mammal Species of the World