{{Taxobox
| color = pink
| name = Kašelott
| image = sperm whale1b.jpg
| image_width = 250px
| image_caption = Kašelott
| image2 = Sperm_whale_size.svg
| image2_width = 250px
| image2_caption = Suurus võrrelduna keskmise inimesega
| regnum = Loomad ''Animalia''
| phylum = Keelikloomad ''Chordata''
| classis = Imetajad ''Mammalia''
| ordo = Vaalalised ''Cetacea''
| subordo = Hammasvaalalised ''Odontoceti''
| familia = Kašelotlased ''Physteridae''
| genus = '''''Physeter'''''
| species = '''''P. macrocephalus'''''
| binomial = ''Physeter macrocephalus''
| binomial_authority = Linné, 1758
| range_map = cetacea range map Sperm Whale 4.PNG
| range_map_width = 250px
| range_map_caption= Kašeloti levila
}}
'''Kašelott''' ehk '''võidisvaal''' (''Physeter macrocephalus'') on kašelotlaste hammasvaalaline.

==Kehaehitus==

Kašelottide isas- ja emasloomad erinevad üksteisest mõõtmete poolest. Isased võivad kasvada 16–18 meetri pikkuseks ja kaaluda kuni 50 tonni, emasloomad võivad kasvada aga 12–14 meetri pikkuseks ja kaaluda kuni 25 tonni.

Ulatusliku vaalapüügi tagajärjel on vähenenud tunduvalt kašelottide suurus, kuna enamasti püüti just võimalikult suuri isendeid. Säilinud skelettide järgi on avastatud, et veel paar sajandit tagasi võis kohata kuni 28-meetriseid kašelotte. Need isendid olid suuruselt võrreldavad heeringavaalaga, mistõttu võiks neid lugeda sinivaala järel suuruselt teisteks loomadeks.

Kašelottidel on väga suur eest tömp ja külgedelt kokkusurutud pea, mis moodustab kuni kolmandiku keha üldpikkusest. Isaste kašelottide pea on suurem kui emasloomade oma. Pikliku kujuga hingats paikneb pea vasakus eesnurgas. Parempoolne ninakanal ei avane välja, vaid ühineb ees ja taga mahukate õhukottidega. 

Pea omapärane kuju on tingitud ülalõua kohal paiknevast padjandist, kus toodetakse vaalavõidist ehk spermatseeti.

Kašeloti aju kaalub keskmiselt 7 kg, mis on suurem kui ühelgi teisel loomal.

Suuõõne ehitus võimaldab kašelottidel saaki endasse "imeda".

Kašelottide seljauim sarnaneb paksu madala küüruga ning selle taga leidub veel mitu väiksemat küüru. 

Alalõuas paikneb 20–26 paari emailita hambaid, millest suurimad kaaluvad ligi 1,6 kg. 

Kehavärvus varieerub hallikaspruunist kuni mustjaspruunini. Keha alumine pool on veidi heledam ning nabapiirkond ja mokad on harilikult valged. On kohatud ka albiinokašelotte.

==Eluviis==

Kašelotid elavad karjadena pea kogu maailmameres. Isas- ja emasloomad moodustavad reeglina eraldi karju. 

Isased on levinud laiemalt kui emased, kuna nad rändavad rohkem. Suvel jõuavad nad põhjas Barentsi ja Beringi merre ning lõunas Antarktika vetesse. 

Emased elavad ning sigivad troopikavetes ja ületavad harva subtroopilise vööndi piire. Emaste karjas on harilikult 10–15 emaslooma ja noored, mitte veel suguküpsed, vaalad.

Sigimisperioodil leidub ka noorte isasloomade karju ning suuri haaremeid, kuhu kuuluvad emased, nende pojad ning üks suguküps isane.

==Sigimine ja areng==

Sügiseti rändavad isaskašelottide karjad polaaraladelt ekvaatori lähistele, kus toimub sigimine. 

Suuremad ja tugevamad isased püüavad endale koguda kuni 30 emasest ja nende poegadest koosnevat karja. Selle käigus läheb isastel sageli ägedateks lahinguteks. 

Haaremi valitsejaks saanud isasloom paaritub kõigi emasloomadega, välja arvatud tiined või väikeste poegadega emased. Pärast paaritumist püsib isasloom veel mõnda aega koos karjaga.

{{Taxobox
| name = Sperm whale
| status = VU
| status_system = iucn3.1
| status_ref =<ref> Database entry includes a lengthy justification of why this species is vulnerable </ref>
| image = sperm whale1b.jpg
| image_caption = ''Scarred Giant'' (detail)— Artist: [http://www.velvetgreencreations.com/index.php?page=Marine_Life_Art&list=0&item=1194396073&archive=0 Chris Harman]
| image2 = Sperm_whale_size.svg
| image2_caption = Size comparison against an average human
| regnum = Animalia
| phylum = Chordata
| classis = Mammalia
| ordo = Cetacea
| subordo = Odontoceti
| familia = Physeteridae
| genus = '''''Physeter'''''
| species = '''''P. catodon'''''
| binomial = ''Physeter catodon''
| binomial_authority = Linnaeus, 1758
| synonyms = 
'''''P. macrocephalus''''' <small>Linnaeus, 1758</small>
| range_map = cetacea range map Sperm Whale 4.PNG
| range_map_caption= Sperm whale range (in blue)
}}

The '''sperm whale''' ('''''Physeter catodon''''') is the largest of all toothed whales and largest living toothed animal. The whale was named after the milky-white waxy substance, spermaceti, found in its head and originally mistaken for sperm. It has a cosmopolitan distribution across the world's oceans. The species feeds on squid and fish, diving as deep as  in order to obtain its prey, making it the deepest diving mammal in the world. Pods of females and young live separately from older males. Sperm whales live for 50 years and possibly more.

The sperm whale's enormous head and distinctive shape, as well as its central role in archetypal whale. Partly because of Melville, the sperm whale is commonly associated with the Portuguese (''cachalote''), probably coming from ''cachola'', a colloquial term for ''head''. Sperm whales were commercially hunted until recently, declined as a consequence of over-harvesting, and are currently listed as IUCN.

== Description ==

thumb|200px|left|Head anatomy
Sperm whales are the largest toothed whales, with adult males measuring up to  long.<ref name=marinebio>[http://marinebio.org/species.asp?id=190 ''Physeter catodon'', Sperm Whale] at [http://marinebio.org/ marinebio.org]</ref>  Their distinctive shape comes from their very large head, particularly in males, which is typically one-third of the animal's length. In contrast to the smooth skin of most other large whales, the skin on the back of the sperm whale is usually knobbly and has been likened to a prune by whale-watching enthusiasts.<ref name="prune"></ref> They are uniformly grey in colour, though they may appear brown in sunlight; white largest and heaviest known of any modern or extinct animal (weighing on average  in a grown male).<ref></ref> However, the brain proportionately weighs less than half the brain size of a human when body size is factored.

The blowhole is situated very close to the front of the head and shifted to the whale's left. This gives rise to a distinctive bushy blow angled forward.
The sperm whale has no true dorsal fin, instead a series of ridges are present on the caudal third of the back. The largest was called the 'hump' by whalers and is commonly mistaken for a dorsal fin because of its shape.

left|frame|The flukes of a sperm whale as it dives into the [[Gulf of Mexico (courtesy NMFS)]]
The fluke is also triangular and very thick. Flukes are lifted very high out of the water before a whale begins a deep dive.

Sperm whales have 20–26 pairs of cone-shaped cm (3–8&nbsp;in) long.<ref></ref> Each tooth can weigh as much as one kilogram. The reason for the existence of the teeth is not known with certainty. It is believed that they are not necessary for feeding on squid and indeed healthy well-fed sperm whales have been found in the wild without teeth. The current scientific consensus is that the teeth may be used for aggression between males of the same species. This hypothesis is consistent with the conic shape and wide spacing of the teeth.<ref>[http://www.whale-images.com/sperm_whale_facts.jsp Sperm Whale Facts]. Retrieved December 26, 2007.</ref> Furthermore bull sperm whales often show scars which seem to be caused by the teeth of other bulls. Rudimentary teeth are also present in the upper jaw, but these rarely open into the mouth.

Sperm whales are amongst the most sexually dimorphic (that is, males and females differ greatly) of all cetaceans. Males are typically 30% to 50% longer (16-18&nbsp;m, 52–59&nbsp;ft) than females (12-14&nbsp;m, 39–46&nbsp;ft) and are twice as massive (50&nbsp;000&nbsp;kg vs. 25&nbsp;000&nbsp;kg, 55&nbsp;short tons vs 27.5&nbsp;short&nbsp;tons). At birth both males and females are about 4&nbsp;m (13&nbsp;ft) in length and mass of 1&nbsp;000&nbsp;kg (1&nbsp;tonne).

The largest bull sperm whale verified and accurately measured was 20.5 m (67.9 ft) and 80 tonnes (88 tons).<ref>Wood, The Guinness Book of Animal Facts and Feats. Sterling Pub Co Inc (1983), ISBN 978-0851122359</ref> However, there is evidence of much larger bulls than this. Owing to extensive whaling, sperm whale size may have decreased dramatically, as males were heavily exploited during the modern era, primarily after World War II. In a Nantucket museum there is a jawbone of a sperm whale which is 5.5&nbsp;m (18&nbsp;ft). The jawbone makes up to 20%-25% of the sperm whale's overall body length. Thus this whale might have been at most 28&nbsp;m (90&nbsp;ft) long, a mass of around 133&nbsp;metric tons (150&nbsp;short&nbsp;tons). Further evidence of larger bulls in the past resides in New Bedford museum, a 5.2 metres (17&nbsp;ft) jaw of a bull that could have been about 25.6 metres (84&nbsp;ft) long, with a maximum mass of about 120&nbsp;tons. In addition, logbooks found in the Nantucket and New Bedford museums are filled with references to bulls that were, considering the amount of oil they yielded, about the same size as these two examples- although whalers were notorious for exaggerating the yield of oil and length of whales they caught. Today, sperm whale males do not usually exceed 18&nbsp;m (60&nbsp;ft) in length and 52 metric tons (57 short tons). The largest sperm whales observed are comparable in size to the fin whale (and smaller than blue whales), making the sperm whale either the second or third largest animal species alive.

=== Spermaceti ===

Spermaceti is the semiliquid, waxy substance found in the head of the sperm whale. The name derives from the late Latin ''sperma ceti'' (both words actually loaned from Greek) meaning "sperm of the whale" (strictly, "sperm of the sea monster"). The common name for the species is actually an apocopation of Spermaceti Whale. Early whalers mistook the substance for the whale's semen. Spermaceti is found in the ''spermaceti organ'' or ''case'' in front of and above the skull of the whale and also in the so-called ''junk'' which is right at the front of the whale's head just above the upper jaw. The case consists of a soft white, waxy substance saturated with spermaceti. The junk is a more solid substance.

One function of the spermaceti organs is a buoyancy or diving organ. Before diving, cold water is brought through the organ and the wax is solidified. The increase in specific density generates a down force (approx 40&nbsp;kg equiv) and allows the whale effortless sinking. During the chase in deep levels (max&nbsp;3,000m) the stored oxygen is consumed and excess heat melts the spermaceti. Now only hydrodynamic forces (by swimming) keep the whale down before effortlessly surfacing.

Hypotheses on further functions exist: One incidentally discussed in ''Moby-Dick'' by Melville, is that the case evolved as a kind of battering ram for use in fights between males.<ref name="battering"></ref> This hypothesis is consistent with the well-documented sinking of the ships ''Essex'' and ''Ann Alexander'' due to attacks by sperm whales estimated to weigh only one-fifth as much as the ships.

Another possibility is that the case is used as an aid to echolocation (see melon). The shape of the organ at any given time is likely to focus or widen the beam of emitted sound.<ref name="cranford">[http://www.spermwhale.org/SDSU/cranford.html spermwhale.org] - Cranford</ref> The sperm whale actually has two nostrils — one external nostril, forming the blow hole, and one internal nostril pressing against the bag-like spermaceti container.

Spermaceti was much sought after by 18th, 19th and 20th century whalers. The substance found a variety of commercial applications, such as watch oil, automatic transmission fluid, lubricant for photographic lenses and delicate high-altitude instruments, cosmetics, additives in motor oils, glycerine, rust-proofing compounds, detergent, chemical fibres, vitamins and 70 or more pharmaceutical compounds.

==Distribution==

The Sperm Whale is among the most continental shelves and canyons, probably because of easier feeding. 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, such as off the Azores or the Caribbean island of Dominica.

== Ecology, behaviour and life history ==

Sperm whales are a prime example of a species that has been K-selected, a Nursing takes place for two to three years. In males, puberty lasts for about ten years between the ages of about 10 and 20. Males continue to grow into their 30s and 40s and only reach their full size when about 50 years old. Sperm whales live for up to 80 years.

The social structure of the sperm whales species divides on sexual lines. Females are extremely social animals. Females stay in groups of about a dozen individuals and their young. Males leave these "nursery schools" at somewhere between 4 and 21 years of age and join a "bachelor school" with other males of a similar age and size. As males grow older, they tend to disperse into smaller groups, and the oldest males typically live solitary lives. Yet mature males have been stranded on beaches together, suggesting a degree of co-operation not yet fully understood.

The only predator that attacks sperm whales, besides human beings, is the Orca.<ref>Pitman, RL; Ballance, LT; Mesnick, SI; Chivers, SJ (2001) "Killer whale predation on sperm whales: Observations and implications" ''Marine Mammal Science'' '''17'''(3): 494-507 [http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=5136745&q=&uid=788845644&setcookie=yes Abstract]</ref> Large, roving pods of Orcas frequently target groups of females with young, usually trying to separate the sperm whale calf and kill it. Often, the female sperm whales can repel these attacks by forming a circle with their calves in the centre and then violently thrashing their tail flukes, so that no Orca can penetrate the formation. If the Orca pod is extremely large, they may sometimes also kill adult females. Large bull sperm whales have no non-human predators, as even Orcas could be killed by these aggressive, powerful creatures.

=== Feeding ===
thumb|200px|A piece of sperm whale skin with giant squid sucker scars

Sperm whales feed on several species, notably demersal rays, but the main part of their diet consists of medium sized squid. Most of what is known about deep sea squid has been learned from specimens found in captured sperm whale stomachs, although more recent studies have analysed fecal matter instead. One study, carried out around the Galápagos, found that squid from the genera ''Histioteutbis'' (62%), ''Ancistrocbeirus'' (16%), and ''Octopoteutbis'' (7%) were the most commonly taken,<ref>Smith S., &Whitehead (2000) The Diet of Galapagos sperm whales ''Physeter macrocephalus'' as indicated by fecal sample analysis" ''Marine Mammal Science'' '''16''' (2) , 315–325 doi:10.1111/j.1748-7692.2000.tb00927.x </ref> and that most squid were between 12-650 kg in weight. An older study, examining the contents of whales captured by the New Zealand whaling fleet in the Cook Strait region, found a 1.69:1 ratio of squid to fish by weight.<ref>GaskinD. & Cawthorn M. (1966) "Diet and feeding habits of the sperm whale (''Physeter macrocephalus'' L.) in the Cook Strait region of New Zealand" ''New Zealand Journal of Marine and Freshwater Research'' '''2''': 156-79 [http://www.rsnz.org/publish/nzjmfr/1967/15.pdf] </ref> Stealing of Sablefish and Toothfish from long lines has been documented and well known also (see below). Battles between sperm whales and colossal squid (which have been measured to weigh nearly 500 kg) have never been observed by humans, however white scars on the bodies of sperm whales are believed to be caused by squid. In one case three Sperm Whales were observed attacking or playing with a megamouth shark, a rare and large deep-sea species only discovered by man in the 1970s.<ref>Compagno, L. J. V., (2001). Sharks of the world. An annotated and
illustrated catalogue of shark species known to date. Volume 2. Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). ''FAO Species Catalogue for Fishery Purposes''. '''1''' (2): Rome. Pp. 74-78 [ftp://ftp.fao.org/docrep/fao/009/x9293e/x9293e00.pdf] </ref>

It is hypothesised that the sharp beak of a consumed squid lodged in the whale's intestine leads to the production of ambergris, analogous to the production of pearls.<ref>Dannenfeldt K.H. (1982). "Ambergris: The Search for Its Origin" ''Isis'' '''73'''(3): 382-397. [http://www.jstor.org/view/00211753/ap010218/01a00040/0 abstract] </ref>  The irritation of the intestines caused by the beaks stimulates the secretion of this lubricant-like substance. Sperm whales are prodigious feeders and eat around 3% of their body weight per day. The total annual consumption of prey by sperm whales worldwide is estimated to be about 100 million tons — a figure greater than the total consumption of marine animals by humans each year.<ref>Richard Ellis, ''Monsters of the Sea'', 1994, The Lyons Press, p. 245.</ref>

It is difficult to see why the sperm whale has such a large head in comparison to the lower jaw. One theory explaining this is that the Sperm Whale's ability to echolocate through its head aids in hunting. Within the head, it contains a structure called monkey lips, which it blows air through. This can create clicks that have a source level exceeding 230 dB re 1 micropascal referenced to a distance of 1&nbsp;metre.<ref>B. Møhl M. Wahlberg, P. T. Madsen, A. Heerfordt and A. Lund, The monopulsed nature of sperm whale clicks, J. Acoust. Soc. Am. 114, 1143-1153 (2003).</ref> It has been hypothesised that these were directed at prey in order to stun them, however experimental studies attempting to duplicate this effect have been unable to replicate the supposed injuries, and have cast doubt on this idea.<ref>Benoit-Bird K. Au W. & Kastelein R. (2006) "Testing the odontocete acoustic prey debilitation hypothesis: No stunning results". '' The Journal of the Acoustical Society of America'' '''120''' (2): 1118-1123 ([http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JASMAN000120000002001118000001&idtype=cvips&gifs=yes Abstract])</ref>

Long-line fishing operations in the Gulf of Alaska have complained that numerous sperm whales have taken advantage of their fishing operations to eat desirable species straight off the line, sparing the whales the need to hunt them themselves. However, the amount of fish taken is very little compared to what the sperm whale needs per day. New video footage has been captured of a large male sperm whale "bouncing" a long line, to gain the fish.<ref></ref>

=== Diving and breathing ===

Sperm whales, along with bottlenose whales and elephant seals, are the deepest-diving mammals in the world. Sperm whales are believed to be able to dive up to 3&nbsp;km (1.9&nbsp;miles) in depth and 90 minutes in duration to the ocean floor. More typical dives are around 400&nbsp;m (437&nbsp;yards) in depth and 30–45 minutes' duration and generally move in a northerly direction. They carry three tonnes of blood which holds enough oxygen to help it achieve its diving depth.

The physiology of the sperm whale has several adaptations to cope with drastic changes in pressure when diving. The ribcage is flexible to allow lung collapse, and the heart rate can decrease to preserve oxygen supplies. Myoglobin stores oxygen in muscle tissue. Blood can be directed towards the brain and other essential organs only, when oxygen levels deplete. The spermaceti organ may also play a role (see above).

Because of the great depths to which they dive, sperm whales sometimes drown when entangled in transoceanic telephone cables.<ref>The Southwestern Company: "The Volume Library 1", page 65, 1987, ISBN 0-87197-208-5</ref>

While sperm whales are well adapted to diving, repeated dives to great depths do have long term effects on the whales. Skeletons of sperm whales show pitting of the bones that is often a sign of decompression sickness in humans. Skeletons of the oldest whales showed the most extensive pitting, whereas skeletons of sperm whale calves showed no damage. This damage may indicate that sperm whales are susceptible to decompression sickness, and sudden surfacing could be lethal to them.<ref name="bends"></ref>

Between dives, the sperm whale will come up to the surface for breath and remain more or less still for eight to ten minutes before diving again. Odontoceti (toothed whales) breathe air at the surface of the water through a single, s-shaped blowhole. The blowhole is located on the left side of the front of the head. Sperm whales spout (breathe) 3–5 times per minute at rest, but the rate increases to 6–7 times per minute after a dive. The blow is a noisy, single stream that rises up to 15&nbsp;m (50&nbsp;ft) above the surface of the water and points forward and to the left of the whale at a 45° angle.

== Taxonomy and naming ==

The sperm whale is one of the many species originally described by Linnaeus in 1758 in his 18th century work, ''Systema Naturae''; he recognised four species in the genus ''Physeter''.<ref> </ref> Experts soon realised that just one such species exists, although its correct name is a matter of dispute (see below), with some workers using the name ''Physeter catodon'' (e.g. see this [http://scholar.google.com.au/scholar?q=physeter+catodon Google Scholar search]) but others using ''Physeter macrocephalus'' (as per [http://scholar.google.com.au/scholar?q=physeter+macrocephalus this search]).

The sperm whale is the sole extant species of its genus, ''Physeter'', which is placed in the family Physeteridae. Two species of the related extant genus ''Kogia'', the pygmy sperm whale ''Kogia breviceps'' and the dwarf sperm whale ''K. simus'', are sometimes also placed in this family, but more often in their own family, Kogiidae.