Wednesday, March 9, 2011
March 9, 2011 : Sperm Whale
The sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale (odontocete) having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter. The synonym Physeter catodon refers to the same species. It is one of three extant species in the sperm whale superfamily, along with the pygmy sperm whale and dwarf sperm whale.
A bull can grow to 20.5 metres (67 ft) long. It is the largest living toothed animal. The head can take up to one-third of the animal's length. It has a cosmopolitan distribution across the oceans. The species feeds on squid and fish, diving as deep as 3 kilometres (9,800 ft), which makes it the deepest diving mammal. Its diet includes giant squid and colossal squid. The sperm whale's clicking vocalization is the loudest sound produced by any animal, but its functions are uncertain. These whales live in groups called pods. Pods of females and their young live separately from older males. The females cooperate to protect and nurse their young. Females give birth every three to six years, and care for the calves for more than a decade.
Historically, the sperm whale was also known as the common cachalot; "cachalot" is derived from an archaic French word for "tooth". Over most of the period from the early 18th century until the late 20th century, the sperm whale was hunted to obtain spermaceti and other products, such as sperm oil and ambergris. Spermaceti found many important uses, such as candles, soap, cosmetics and machine oil. Due to its size, the sperm whale could sometimes defend itself effectively against whalers. In the most famous example, a sperm whale attacked and sank the American whaleship Essex in 1820. As a result of whaling, the sperm whale is currently listed as vulnerable by the IUCN. The sperm whale has few natural predators, since few are strong enough to successfully attack a healthy adult; orcas attack pods and kill calves. The sperm whale can live for more than 70 years.
The name sperm whale is an apocopation of spermaceti whale. Spermaceti is the semi-liquid, waxy substance found in the spermaceti organ or case in front of and above the skull bone and also in the junk, the area below the spermaceti organ and just above the upper jaw. The case consists of a soft white, waxy substance saturated with spermaceti oil. The junk is composed of cavities filled with the same wax and spermaceti oil and intervening connective tissue. The sperm whale is also known as the "cachalot", which is thought to derive from the archaic French for "tooth" or "big teeth", as preserved for example in cachau in the Gascon dialect (a word of either Romance or Basque origin). The etymological dictionary of Corominas says the origin is uncertain, but it suggests that it comes from the vulgar Latin cappula, plural of cappulum, sword hilt. According to Encarta Dictionary, the word cachalot came to English "via French from Spanish or Portuguese cachalote, perhaps from [Portuguese] cachola, 'big head'".