Sperm whale
The sperm whale or cachalot[a] (Physeter macrocephalus) is the largest of the toothed whales and the largest toothed predator. It is the only living member of the 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.
"Cachalot" redirects here. For other uses, see Cachalot (disambiguation).
The sperm whale is a pelagic mammal with a worldwide range, and will migrate seasonally for feeding and breeding.[5] Females and young males live together in groups, while mature males (bulls) 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, healthy sperm whale has no natural predators, although calves and weakened adults are sometimes killed by pods of killer whales (orcas).
Mature males average 16 metres (52 ft) in length, with the head representing up to one-third of the animal's length. Plunging to 2,250 metres (7,380 ft), it is the third deepest diving mammal, exceeded only by the southern elephant seal and Cuvier's beaked whale.[6][7] The sperm whale uses echolocation and vocalization with source level as loud as 236 decibels (re 1 μPa m) underwater,[8][9] the loudest of any animal.[10] It has the largest brain on Earth, more than five times heavier than a human's. Sperm whales can live 70 years or more.[11][12][13]
Sperm whales' heads are filled with a waxy substance called "spermaceti" (sperm oil), from which the whale derives its name. Spermaceti was a prime target of the whaling industry and was sought after for use in oil lamps, lubricants, and candles. Ambergris, a solid waxy waste product sometimes present in its digestive system, is still highly valued as a fixative in perfumes, among other uses. Beachcombers look out for ambergris as flotsam.[14] Sperm whaling was a major industry in the 19th century, depicted in the novel Moby-Dick. The species is protected by the International Whaling Commission moratorium, and is listed as vulnerable by the International Union for Conservation of Nature.
Taxonomy and naming
Etymology
The name "sperm whale" is a clipping of "spermaceti whale". Spermaceti, originally mistakenly identified as the whales' semen, is the semi-liquid, waxy substance found within the whale's head.[15]
(See "Spermaceti organ and melon" below.)
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 the word caishau in the Gascon dialect (a word of either Romance[16]
or Basque[17]
origin).
The etymological dictionary of Corominas says the origin is uncertain, but it suggests that it comes from the Vulgar Latin cappula 'sword hilts'.[18] The word cachalot came to English via French from Spanish or Portuguese cachalote, perhaps from Galician/Portuguese cachola 'big head'.[19]
The term is retained in the Russian word for the animal, kashalot (кашалот), as well as in many other languages.
The scientific genus name Physeter comes from the Greek physētēr (φυσητήρ), meaning 'blowpipe, blowhole (of a whale)', or – as a pars pro toto – 'whale'.
The specific name macrocephalus is Latinized from the Greek makroképhalos (μακροκέφαλος 'big-headed'), from makros (μακρός) + kephalē (κεφαλή).
Its synonymous specific name catodon means 'down-tooth', from the Greek elements cat(a)- ('below') and odṓn ('tooth'); so named because it has visible teeth only in its lower jaw.[20] (See "Jaws and teeth" below.)
Another synonym australasianus ('Australasian') was applied to sperm whales in the Southern Hemisphere.[21]
Taxonomy
The sperm whale belongs to the order Cetartiodactyla,[22] the order containing all cetaceans and even-toed ungulates. It is a member of the unranked clade Cetacea, with all the whales, dolphins, and porpoises, and further classified into Odontoceti, containing all the toothed whales and dolphins. It is the sole extant species of its genus, Physeter, in the family Physeteridae. Two species of the related extant genus Kogia, the pygmy sperm whale Kogia breviceps and the dwarf sperm whale K. sima, are placed either in this family or in the family Kogiidae.[23] In some taxonomic schemes the families Kogiidae and Physeteridae are combined as the superfamily Physeteroidea (see the separate entry on the sperm whale family).[24]
Swedish ichthyologist Peter Artedi described it as Physeter catodon in his 1738 work Genera piscium, from the report of a beached specimen in Orkney in 1693 and two beached in the Netherlands in 1598 and 1601.[25] The 1598 specimen was near Berkhey.
The sperm whale is one of the species originally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. He recognised four species in the genus Physeter.[26] Experts soon realised that just one such species exists, although there has been debate about whether this should be named P. catodon or P. macrocephalus, two of the names used by Linnaeus. Both names are still used, although most recent authors now accept macrocephalus as the valid name, limiting catodon's status to a lesser synonym. Until 1974, the species was generally known as P. catodon. In that year, however, Dutch zoologists Antonius M. Husson and Lipke Holthuis proposed that the correct name should be P. macrocephalus, the second name in the genus Physeter published by Linnaeus concurrently with P. catodon.
This proposition was based on the grounds that the names were synonyms published simultaneously, and, therefore, the ICZN Principle of the First Reviser should apply. In this instance, it led to the choice of P. macrocephalus over P. catodon, a view re-stated in Holthuis, 1987.[27] This has been adopted by most subsequent authors, although Schevill (1986[28] and 1987[29]) argued that macrocephalus was published with an inaccurate description and that therefore only the species catodon was valid, rendering the principle of "First Reviser" inapplicable. The most recent version of ITIS has altered its usage from P. catodon to P. macrocephalus,[30] following L. B. Holthuis and more recent (2008) discussions with relevant experts.[31][32] Furthermore, The Taxonomy Committee of the Society for Marine Mammalogy, the largest international association of marine mammal scientists in the world, officially uses Physeter macrocephalus when publishing their definitive list of marine mammal species.[33]
The phonic lips.
The frontal sac, exposed. Its surface is covered with fluid-filled knobs.
A piece of the posterior wall of the frontal sac. The grooves between the knobs trap a consistent film of air, making it an excellent sound mirror.[103]
![A piece of the posterior wall of the frontal sac. The grooves between the knobs trap a consistent film of air, making it an excellent sound mirror.[103]](http://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Sperm_whale_frontal_sac_surface_close-up.jpg/101px-Sperm_whale_frontal_sac_surface_close-up.jpg)