Following the reports of attacks that inspired the Moby-Dick tale from classic literature, an investigative team searches for albino sperm whales to see if there is any truth to their aggressive nature. The sperm whale (Physeter macrocephalus) is the largest of the toothed whales. 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. Its name derives from a waxy liquid called spermaceti, found in its enormous head. The sperm whale is also known as the cachalot. Mature males average at 16 metres (52 ft) in length but can reach 20.5 metres (67 ft), with the head representing up to one-third of the animal's length. The sperm whale feeds primarily on giant and colossal squid. Plunging to 3 kilometres (9,800 ft) for prey, it is the deepest diving mammal. Its clicking vocalization, a form of echolocation and communication, can be as loud as 230 decibels underwater, making it the loudest sound produced by any animal. It has the largest brain of any animal on Earth, more than five times heavier than a human's. The sperm whale is cosmopolitan, living across the world's oceans in small groups called pods. Units of females and their young live separately from sexually mature males. 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. Living up to 70 years, a mature sperm whale has few natural predators. Calves and weakened adults are taken by pods of orcas. From the early 18th century through the late 20th the species was a prime target of whalers. The head of the whale contains a liquid wax called spermaceti, which was used in lubricants, oil lamps, and candles. Ambergris, a waste product from its digestive system, is still used as a fixative in perfumes. Occasionally the sperm whale's great size allowed it to defend itself effectively against whalers. The species is now protected by a whaling moratorium, and is currently listed as vulnerable by the IUCN. Distribution The sperm whale is among the most cosmopolitan species. It prefers ice-free waters over 1,000 metres (3,300 ft) deep. Although both sexes range through temperate and tropical oceans and seas, only adult males populate higher latitudes. It is relatively abundant from the poles to the equator and is found in all the oceans. It inhabits the Mediterranean Sea, but not the Black Sea, while its presence in the Red Sea is uncertain. The shallow entrances to both the Black Sea and the Red Sea may account for their absence. The Black Sea's lower layers are also anoxic and contain high concentrations of sulphur compounds such as hydrogen sulphide. Populations are denser close to continental shelves and canyons. Sperm whales are usually found in deep off-shore waters, but may be seen closer to shore in areas where the continental shelf is small and drops quickly to depths of 310--920 metres (1,020--3,020 ft). Coastal areas with significant sperm whale populations include the Azores and the Caribbean island of Dominica.[

• published: 10 Jun 2013
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