Sperm Whale

The **sperm whale** (*Physeter macrocephalus*) or **cachalot** /ˈkæʃəˌlɒt, ˈkæʃəˌloʊ/ is the largest of the toothed whales and the largest toothed predator. It is the only living member of genus ***Physeter*** and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus *Kogia*.

The sperm whale is a pelagic mammal with a worldwide range, and will migrate seasonally for feeding and breeding. Females and young males live together in groups while mature males live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade. A mature sperm whale has few natural predators, although calves and weakened adults are sometimes killed by pods of orcas.

Mature males average 16 metres (52 ft) in length but some may reach 20.5 metres (67 ft), with the head representing up to one-third of the animal's length. Plunging to 2,250 metres (7,382 ft), it is the second deepest diving mammal, following only the Cuvier's beaked whale.

The sperm whale is a prominent user of echolocation and communication, with vocalization as loud as 230 decibels (re 1 µPa at 1 m) underwater. It has the largest brain of any animal on Earth, more than five times heavier than a human's. Sperm whales can live for more than 60 years.

Spermaceti oil (called "sperm" for short), from which the whale derives its name, was a prime target of the whaling industry, and was dominant for use in oil lamps, lubricants, and candles. Ambergris is a solid waxy waste product from its digestive system. It is still highly valued as a fixative in perfumes and other uses. It remains as flotsam from deceased whales, and is sought by beachcombers. The species is now protected by a whaling moratorium, and is currently listed as vulnerable by the International Union for Conservation of Nature (IUCN).

## Description

The sperm whale is the largest toothed whale, with adult males measuring up to 20.5 metres (67 ft) long and weighing up to 57,000 kilograms (56 long tons; 63 short tons). By contrast, the second largest toothed whale (Baird's Beaked Whale) measures 12.8 metres (42 ft) and weighs up to 15 short tons (14,000 kg). The Nantucket Whaling Museum has a 5.5 metres (18 ft)-long jawbone. The museum claims that this individual was 24 metres (80 ft) long; the whale that sank the *Essex* (one of the incidents behind *Moby-Dick*) was claimed to be 26 metres (85 ft). A similar size is reported from a jawbone from the British Natural History Museum. A 20m specimen is reported from a Soviet whaling fleet near the Kuril Islands in 1950. There is disagreement on the claims of adult males approaching or exceeding 24 metres (80 ft) in length.

Extensive whaling may have decreased their size, as males were highly sought, primarily after World War II. Today, males do not usually exceed 18.3 metres (60 ft) in length or 51,000 kilograms (50 long tons; 56 short tons) in weight. Another view holds that exploitation by overwhaling had virtually no effect on the size of the bull sperm whales, and their size may have actually increased in current times on the basis of density dependent effects. Old males taken at Solander Islands were recorded to be extremely large and unusually rich in blubbers.

It is among the most sexually dimorphic of all cetaceans. At birth both sexes are about the same size, but mature males are typically 30% to 50% longer and three times as massive as females.

The sperm whale's unique body is unlikely to be confused with any other species. The sperm whale's distinctive shape comes from its very large, block-shaped head, which can be one-quarter to one-third of the animal's length. The S-shaped blowhole is located very close to the front of the head and shifted to the whale's left. This gives rise to a distinctive bushy, forward-angled spray.

The sperm whale's flukes (tail lobes) are triangular and very thick. Proportionally, they are larger than that of any other cetacean, and are very flexible. The whale lifts its flukes high out of the water as it begins a feeding dive. It has a series of ridges on the back's caudal third instead of a dorsal fin. The largest ridge was called the 'hump' by whalers, and can be mistaken for a dorsal fin because of its shape and size.

In contrast to the smooth skin of most large whales, its back skin is usually wrinkly and has been likened to a prune by whale-watching enthusiasts. Albinos have been reported.

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