Sperm whales dive deeper than almost any mammal—and louder
Physeter macrocephalus, the cachalot, is the largest toothed whale and predator, sole living Physeter beside pygmy and dwarf kogia relatives. Bulls average sixteen meters with heads up to a third of length, diving to about 2,250 meters on 236-decibel clicks.
Few animals push physiology as far. A bull averages 16 metres, and up to a third of that is head, housing the largest brain on Earth, more than five times the weight of a human's. The whale dives as deep as 2,250 metres, a depth that among mammals only Cuvier's beaked whale and the southern elephant seal exceed, and its clicks reach 236 decibels, louder than any other animal. Males end up 30 to 50 percent longer and about three times heavier than females, though calves of both sexes are born at 3.5 to 4.5 metres. Individuals can live past 70.
Its life is split by sex. Females and young males travel in groups where mothers share protection and nursing, give birth only every four to twenty years, and look after each calf for over a decade. Adult bulls roam alone outside the breeding season. Healthy adults have no natural enemies, though orca pods sometimes kill calves or weak animals.
The names record old misunderstandings. Sperm whale is short for spermaceti whale, after the waxy fluid in the head that early whalers took for semen. Cachalot came to English through French from Spanish or Portuguese, perhaps from a word for big head, and survives in Russian as kashalot. Physeter is Greek for blowhole, and macrocephalus means big-headed. Linnaeus listed four species in 1758; experts soon found only one, and the macrocephalus name won out over catodon, down-tooth, after a 1974 proposal by two Dutch zoologists.
Spermaceti fuelled lamps and candles and made sperm whaling a great nineteenth-century industry, the world of Moby-Dick. Ambergris from the gut is still prized in perfume. The species is now protected by the whaling moratorium but remains vulnerable.
Source: Sperm whale
