Sperm whale
Sperm whale[1] Temporal range:
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Infraorder: | Cetacea |
Family: | Physeteridae
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Genus: | Physeter |
Species: | P. macrocephalus
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Binomial name | |
Physeter macrocephalus | |
Major sperm whale grounds | |
Synonyms | |
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The sperm whale or cachalot.
The sperm whale is a
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 (7,382 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] It has the largest brain on Earth, more than five times heavier than a human's. Sperm whales can live 70 years or more.[10][11][12]
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.[13] 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.[14] (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
or Basque[16] origin).The etymological dictionary of Corominas says the origin is uncertain, but it suggests that it comes from the Vulgar Latin cappula 'sword hilts'.[17] The word cachalot came to English via French from Spanish or Portuguese cachalote, perhaps from Galician/Portuguese cachola 'big head'.[18]
The term is retained in the Russian word for the animal, kashalot (кашалот), as well as in many other languages.[citation needed]
The scientific genus name Physeter comes from the Greek physētēr (φυσητήρ), meaning 'blowpipe, blowhole (of a whale)', or – as a pars pro toto – 'whale'.[citation needed]
The specific name macrocephalus is Latinized from the Greek makroképhalos (μακροκέφαλος 'big-headed'), from makros (μακρός) + kephalē (κεφαλή).[citation needed]
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.[19] (See "Jaws and teeth" below.)
Another synonym australasianus ('Australasian') was applied to sperm whales in the Southern Hemisphere.[20]
Taxonomy
The sperm whale belongs to the
Swedish ichthyologist Peter Artedi described it as Physeter catodon in his 1738 work Genera piscium, from the report of a beached specimen in the Orkneys in 1693 and two beached in the Netherlands in 1598 and 1601.[24] The 1598 specimen was near Berkhey.[citation needed]
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.[25] 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
Biology
External appearance
Length | Weight | |
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Male | 16 metres (52 ft) | 45 tonnes (50 short tons) |
Female | 11 metres (36 ft) | 15 tonnes (17 short tons) |
Newborn | 4 metres (13 ft) | 1 tonne (1.1 short tons) |
The sperm whale is the largest toothed whale and is among the most
Newborn sperm whales are usually between 3.7 and 4.3 meters (12 and 14 ft) long.
There are occasional reports of individual sperm whales achieving even greater lengths, with some historical claims reaching or exceeding 80 feet (24 m). One example is the whale that sank the
An individual measuring 20.7 metres (68 ft) was reported from a
In 1853, one sperm whale was reported at 62 feet (19 m) in length, with a head measuring 20 feet (6.1 m).[45] Large lower jawbones are held in the British Natural History Museum and the Oxford University Museum of Natural History, measuring 5 metres (16 ft) and 4.7 metres (15 ft), respectively.[43]
The average size of sperm whales has decreased over the years, probably due to pressure from whaling.[34] 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.[46] Old males taken at Solander Islands were recorded to be extremely large and unusually rich in blubbers.[47]
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
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.[48] The whale lifts its flukes high out of the water as it begins a feeding dive.[35] 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.[10]
In contrast to the smooth skin of most large whales, its back skin is usually wrinkly and has been likened to a
Skeleton
The ribs are bound to the spine by flexible cartilage, which allows the ribcage to collapse rather than snap under high pressure.[51] While sperm whales are well adapted to diving, repeated dives to great depths have long-term effects. Bones show the same avascular necrosis that signals decompression sickness in humans. Older skeletons showed the most extensive damage, whereas calves showed no damage. This damage may indicate that sperm whales are susceptible to decompression sickness, and sudden surfacing could be lethal to them.[52]
Like that of all cetaceans, the spine of the sperm whale has reduced
Like many cetaceans, the sperm whale has a vestigial pelvis that is not connected to the spine.[citation needed]
Like that of other toothed whales, the skull of the sperm whale is asymmetrical so as to aid echolocation. Sound waves that strike the whale from different directions will not be channeled in the same way.[54] Within the basin of the cranium, the openings of the bony narial tubes (from which the nasal passages spring) are skewed towards the left side of the skull.[citation needed]
Jaws and teeth
The sperm whale's lower jaw is very narrow and underslung.
Brain
The sperm whale
The sperm whale's cerebrum is the largest in all mammalia, both in absolute and relative terms. The olfactory system is reduced, suggesting that the sperm whale has a poor sense of taste and smell. By contrast, the auditory system is enlarged. The pyramidal tract is poorly developed, reflecting the reduction of its limbs.[65]
Biological systems
The sperm whale respiratory system has adapted to cope with drastic pressure changes when diving. The flexible
The sperm whale has the longest intestinal system in the world,[71] exceeding 300 m in larger specimens.[72][73] The sperm whale has a four-chambered stomach that is similar to ruminants. The first secretes no gastric juices and has very thick muscular walls to crush the food (since whales cannot chew) and resist the claw and sucker attacks of swallowed squid. The second chamber is larger and is where digestion takes place. Undigested squid beaks accumulate in the second chamber – as many as 18,000 have been found in some dissected specimens.[72][74][75] Most squid beaks are vomited by the whale, but some occasionally make it to the hindgut. Such beaks precipitate the formation of ambergris.[75]
In 1959, the heart of a 22 metric-ton (24 short-ton) male taken by whalers was measured to be 116 kilograms (256 lb), about 0.5% of its total mass.
Senses
Spermaceti organ and melon
Atop the whale's skull is positioned a large complex of organs filled with a liquid mixture of fats and waxes called spermaceti. The purpose of this complex is to generate powerful and focused clicking sounds, the existence of which was proven by Valentine Worthington and William Schevill when a recording was produced on a research vessel in May 1959.[88] The sperm whale uses these sounds for echolocation and communication.[89][90][91][92][93][94][95][96][excessive citations]
The spermaceti organ is like a large barrel of spermaceti. Its surrounding wall, known as the case, is extremely tough and fibrous. The case can hold within it up to 1,900
Below the spermaceti organ lies the "junk" which consists of compartments of spermaceti separated by cartilage. It is analogous to the
Running through the head are two air passages. The left passage runs alongside the spermaceti organ and goes directly to the blowhole, whilst the right passage runs underneath the spermaceti organ and passes air through a pair of phonic lips and into the distal sac at the very front of the nose. The distal sac is connected to the blowhole and the terminus of the left passage. When the whale is submerged, it can close the blowhole, and air that passes through the phonic lips can circulate back to the lungs. The sperm whale, unlike other odontocetes, has only one pair of phonic lips, whereas all other toothed whales have two,[105] and it is located at the front of the nose instead of behind the melon.
At the posterior end of this spermaceti complex is the frontal sac, which covers the concave surface of the cranium. The posterior wall of the frontal sac is covered with fluid-filled knobs, which are about 4–13 mm in diameter and separated by narrow grooves. The anterior wall is smooth. The knobbly surface reflects sound waves that come through the spermaceti organ from the phonic lips. The grooves between the knobs trap a film of air that is consistent whatever the orientation or depth of the whale, making it an excellent sound mirror.[101]
The spermaceti organs may also help adjust the whale's
Herman Melville's fictional story Moby-Dick suggests that the "case" containing the spermaceti serves as a battering ram for use in fights between males.[109] A few famous instances include the well-documented sinking of the ships Essex and Ann Alexander by attackers estimated to weigh only one-fifth as much as the ships.[102]
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The phonic lips.
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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.[101]
Eyes and vision
The sperm whale's eye does not differ greatly from those of other toothed whales except in size. It is the largest among the toothed whales, weighing about 170 g. It is overall ellipsoid in shape, compressed along the visual axis, measuring about 7×7×3 cm. The cornea is elliptical and the lens is spherical. The sclera is very hard and thick, roughly 1 cm anteriorly and 3 cm posteriorly. There are no ciliary muscles. The choroid is very thick and contains a fibrous tapetum lucidum. Like other toothed whales, the sperm whale can retract and protrude its eyes, thanks to a 2-cm-thick retractor muscle attached around the eye at the equator,[110] but are unable to roll the eyes in their sockets.[111]
According to Fristrup and Harbison (2002),[112] sperm whale's eyes afford good vision and sensitivity to light. They conjectured that sperm whales use vision to hunt squid, either by detecting silhouettes from below or by detecting bioluminescence. If sperm whales detect silhouettes, Fristrup and Harbison suggested that they hunt upside down, allowing them to use the forward parts of the ventral visual fields for binocular vision.[citation needed]
Sleeping
For some time researchers have been aware that pods of sperm whales may sleep for short periods, assuming a vertical position with their heads just below or at the surface, or head down.[113] A 2008 study published in Current Biology recorded evidence that whales may sleep with both sides of the brain. It appears that some whales may fall into a deep sleep for about 7 percent of the time, most often between 6 p.m. and midnight.[114]
Genetics
Sperm whales have 21 pairs of chromosomes (2n=42).[115] The genome of live whales can be examined by recovering shed skin.[116]
Vocalization complex
After Valentine Worthington and William E. Schevill confirmed the existence of sperm whale vocalization,[88] further studies found that sperm whales are capable of emitting sounds at a volume of 230 decibels – more than an aircraft jet engine at takeoff – making the sperm whale the loudest animal in the world.[117]
Mechanism
When echolocating, the sperm whale emits a directionally focused beam of broadband clicks. Clicks are generated by forcing air through a pair of phonic lips (also known as "monkey lips" or "museau de singe") at the front end of the nose, just below the blowhole. The sound then travels backwards along the length of the nose through the spermaceti organ. Most of the sound energy is then reflected off the frontal sac at the cranium and into the melon, whose lens-like structure focuses it.[89] Some of the sound will reflect back into the spermaceti organ and back towards the front of the whale's nose, where it will be reflected through the spermaceti organ a third time. This back and forth reflection which happens on the scale of a few milliseconds creates a multi-pulse click structure.[118]
This multi-pulse click structure allows researchers to measure the whale's spermaceti organ using only the sound of its clicks.[119][120] Because the interval between pulses of a sperm whale's click is related to the length of the sound producing organ, an individual whale's click is unique to that individual. However, if the whale matures and the size of the spermaceti organ increases, the tone of the whale's click will also change.[120] The lower jaw is the primary reception path for the echoes. A continuous fat-filled canal transmits received sounds to the inner ear.[121]
The source of the air forced through the phonic lips is the right nasal passage. While the left nasal passage opens to the blow hole, the right nasal passage has evolved to supply air to the phonic lips. It is thought that the nostrils of the land-based ancestor of the sperm whale migrated through evolution to their current functions, the left nostril becoming the blowhole and the right nostril becoming the phonic lips.[122]
Air that passes through the phonic lips passes into the distal sac, then back down through the left nasal passage. This recycling of air allows the whale to continuously generate clicks for as long as it is submerged.[123]
Vocalization types
The sperm whale's vocalizations are all based on clicking, described in four types: the usual echolocation, creaks, codas, and slow clicks.[124]
The usual echolocation click type is used in searching for prey.[124] A creak is a rapid series of high-frequency clicks that sounds somewhat like a creaky door hinge. It is typically used when homing in on prey.[124]
Slow clicks are heard only in the presence of males (it is not certain whether females occasionally make them). Males make a lot of slow clicks in breeding grounds (74% of the time), both near the surface and at depth, which suggests they are primarily mating signals. Outside breeding grounds, slow clicks are rarely heard, and usually near the surface.[125]
Click type | Apparent source level (dB re 1 µPa m) |
Directionality | Centroid frequency (kHz) |
Inter-click interval (s) |
Duration of click (ms) |
Duration of pulse (ms) |
Range audible to sperm whale (km) |
Inferred function | Audio sample |
---|---|---|---|---|---|---|---|---|---|
Usual | 230 | High | 15 | 0.5–1.0 | 15–30 | 0.1 | 16 | Searching for prey | |
Creak | 205 | High | 15 | 0.005–0.1 | 0.1–5 | 0.1 | 6 | Homing in on prey | |
Coda | 180 | Low | 5 | 0.1–0.5 | 35 | 0.5 | ~2 | Social communication | |
Slow | 190 | Low | 0.5 | 5–8 | 30 | 5 | 60 | Communication by males |
Codas
The most distinctive vocalizations are codas, which are short rhythmic sequences of clicks, mostly numbering 3–12 clicks, in stereotyped patterns.[126] They are classified using variations in the number of clicks, rhythm, and tempo.[127]
Codas are the result of vocal learning within a stable social group,[128] and are made in the context of the whales' social unit.[126] “The foundation of sperm whale society is the matrilineally based social unit of ten or so females and their offspring. The members of the unit travel together, suckle each others' infants, and babysit them while mothers make long deep dives to feed.”[126] Over 70% of a sperm whale's time is spent independently foraging; codas “could help whales reunite and reaffirm their social ties in between long foraging dives.”[127][129]
While nonidentity codas are commonly used in multiple different clans,[130] some codas express clan identity, and denote different patterns of travel, foraging, and socializing or avoidance among clans.[129][131] In particular, whales will not group with whales of another clan even though they share the same geographical area.[126] Statistically, as the clans' ranges become more overlapped, the distinction in clan identity coda usage becomes more pronounced.[130] Distinctive codas identify seven clans described among the approximately 150,000 female sperm whales in the Pacific Ocean, and there are another four clans in the Atlantic.[126] As “arbitrary traits that function as reliable indicators of cultural group membership,” clan identity codas act as symbolic markers that modulate interactions between individuals.[127]
Individual identity in sperm whale vocalizations is an ongoing scientific issue, however. A distinction needs to be made between cues and signals. Human acoustic tools can distinguish individual whales by analyzing micro-characteristics of their vocalizations,[132] and the whales can probably do the same. This does not prove that the whales deliberately use some vocalizations to signal individual identity in the manner of the signature whistles that bottlenose dolphins use as individual labels.[128][127]
Ecology
Distribution
Sperm whales are among the most
They are relatively abundant from the poles to the equator and are found in all the oceans. They inhabit the
Populations are denser close to
Grown males are known to enter surprisingly shallow bays to rest (whales will be in a state of rest during these occasions). Unique, coastal groups have been reported from various areas around the globe, such as near Scotland's coastal waters,[152] and the Shiretoko Peninsula, off Kaikōura, in Davao Gulf. Such coastal groups were more abundant in pre-whaling days.[153]
Genetic analysis indicates that the world population of sperm whales originated in the Pacific Ocean from a population of about 10,000 animals around 100,000 years ago, when expanding ice caps blocked off their access to other seas. In particular, colonization of the Atlantic was revealed to have occurred multiple times during this expansion of their range.[154]
Diet
Sperm whales usually dive between 300 and 800 metres (980 and 2,620 ft), and sometimes 1 to 2 kilometres (3,300 to 6,600 ft), in search of food.
One study, carried out around the
An older study, examining whales captured by the New Zealand whaling fleet in the
Sperm whales have also been noted to feed on bioluminescent pyrosomes such as Pyrosoma atlanticum.[165][166][167] It is thought that the foraging strategy of sperm whales for bioluminescent squids may also explain the presence of these light-emitting pyrosomes in the diet of the sperm whale.[167]
The sharp beak of a consumed squid lodged in the whale's intestine may lead to the production of
Sperm whales hunt through echolocation. Their clicks are among the most powerful sounds in the animal kingdom (see above). It has been hypothesised that it can stun prey with its clicks. Experimental studies attempting to duplicate this effect have been unable to replicate the supposed injuries, casting doubt on this idea.[172] One study showing that sound pressure levels on the squid are more than an order of magnitude below levels required for debilitation, and therefore, precluding acoustic stunning to facilitate prey capture.[173]
Sperm whales, as well as other large cetaceans, help fertilise the surface of the ocean by consuming nutrients in the depths and transporting those nutrients to the oceans' surface when they defecate, an effect known as the
Life cycle
Sperm whales can live 70 years or more.
How they choose mates has not been definitively determined. Bulls will fight with each other over females, and males will mate with multiple females, making them polygynous, but they do not dominate the group as in a harem.[176][177] Bulls do not provide paternal care to their offspring but rather play a fatherly role to younger bulls to show dominance.[178]
Females become fertile at around 9 years of age.[179] The oldest pregnant female ever recorded was 41 years old.[180] Gestation requires 14 to 16 months, producing a single calf.[10] Sexually mature females give birth once every 4 to 20 years (pregnancy rates were higher during the whaling era).[179] Birth is a social event, as the mother and calf need others to protect them from predators. The other adults may jostle and bite the newborn in its first hours.[181]
Lactation proceeds for 19 to 42 months, but calves, rarely, may suckle up to 13 years.[10] Like that of other whales, the sperm whale's milk has a higher fat content than that of terrestrial mammals: about 36%,[182] compared to 4% in cow milk. This gives it a consistency similar to cottage cheese,[183] which prevents it from dissolving in the water before the calf can drink it.[184] It has an energy content of roughly 3,840 kcal/kg,[182] compared to just 640 kcal/kg in cow milk.[185] Calves may be allowed to suckle from females other than their mothers.[10]
Males become sexually mature at 18 years. Upon reaching sexual maturity, males move to higher latitudes, where the water is colder and feeding is more productive. Females remain at lower latitudes.[10] Males reach their full size at about age 50.[35]
Social behaviour
Relations within the species
Like elephants, females and their young live in matriarchal groups called pods, while bulls live apart. Bulls sometimes form loose bachelor groups with other males of similar age and size. As they grow older, they typically live solitary lives, only returning to the pod to socialize or to breed.[35] Bulls have beached themselves together, suggesting a degree of cooperation which is not yet fully understood.[35] The whales rarely, if ever, leave their group.[186]
A social unit is a group of sperm whales who live and travel together over a period of years. Individuals rarely, if ever, join or leave a social unit. There is a huge variance in the size of social units. They are most commonly between six and nine individuals in size but can have more than twenty.
When sperm whales socialize, they emit complex patterns of clicks called codas. They will spend much of the time rubbing against each other. Tracking of diving whales suggests that groups engage in herding of prey, similar to bait balls created by other species, though the research needs to be confirmed by tracking the prey.[190][191]
Relations with other species
The most common natural predator of sperm whales is the
"Say you strike a Forty-barrel-bull—poor devil! all his comrades quit him. But strike a member of the harem school, and her companions swim around her with every token of concern, sometimes lingering so near her and so long, as themselves to fall a prey."[197]
If the killer whale pod is large, its members may sometimes be able to kill adult female sperm whales and can at least injure an entire pod of sperm whales.[198][199] Bulls have no predators, and are believed to be too large, powerful and aggressive to be threatened by killer whales.[200] Solitary bulls are known to interfere and come to the aid of vulnerable groups nearby.[201] However, the bull sperm whale, when accompanying pods of female sperm whales and their calves as such, may be reportedly unable to effectively dissuade killer whales from their attacks on the group, although the killer whales may end the attack sooner when a bull is present.[202][203]
However, male sperm whales have been observed to attack and intimidate killer whale pods in competitive feeding instances. An incident was filmed from a long-line trawler: a killer whale pod was systematically taking fish caught on the trawler's long lines (as the lines were being pulled into the ship) when a male sperm whale appeared to repeatedly charge the killer whale pod in an attempt to drive them away; it was speculated by the film crew that the sperm whale was attempting to access the same fish. The killer whales employed a tail outward and tail-slapping defensive position against the bull sperm whale similar to that used by female sperm whales against attacking killer whales.[204] However, at some potential feeding sites, the killer whales may prevail over sperm whales even when outnumbered by the sperm whales. Some authors consider the killer whales "usually" behaviorally dominant over sperm whales but express that the two species are "fairly evenly matched", with the killer whales' greater aggression, more considerable biting force for their size and predatory prowess more than compensating for their smaller size.[202][205]
Sperm whales are not known for forging bonds with other species, but it was observed that a bottlenose dolphin with a spinal deformity had been accepted into a pod of sperm whales.
Parasites
Sperm whales can suffer from parasites. Out of 35 sperm whales caught during the 1976–1977 Antarctic whaling season, all of them were infected by Anisakis physeteris (in their stomachs) and Phyllobothrium delphini (in their blubber). Both whales with a placenta were infected with Placentonema gigantissima,[210] potentially the largest nematode worm ever described.[citation needed]
Evolutionary history
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Evolutionary family tree of sperm whales,[211] including simplified summary of extinct groups (†)[212] |
Fossil record
Although the fossil record is poor,[213] several extinct genera have been assigned to the clade Physeteroidea, which includes the last common ancestor of the modern sperm whale, pygmy sperm whales, dwarf sperm whales, and extinct physeteroids. These fossils include Ferecetotherium, Idiorophus, Diaphorocetus, Aulophyseter, Orycterocetus, Scaldicetus, Placoziphius, Zygophyseter and Acrophyseter.[23][212][214] Ferecetotherium, found in Azerbaijan and dated to the late Oligocene (about 28 to 23 million years ago), is the most primitive fossil that has been found, which possesses sperm whale-specific features, such as an asymmetric rostrum ("beak" or "snout").[215] Most sperm whale fossils date from the Miocene period, 23 to 5 million years ago. Diaphorocetus, from Argentina, has been dated to the early Miocene. Fossil sperm whales from the Middle Miocene include Aulophyseter, Idiorophus and Orycterocetus, all of which were found on the West Coast of the United States, and Scaldicetus, found in Europe and Japan.[215][216] Orycterocetus fossils have also been found in the North Atlantic Ocean and the Mediterranean Sea, in addition to the west coast of the United States.[217] Placoziphius, found in Europe, and Acrophyseter, from Peru, are dated to the late Miocene.[23][215]
Fossil sperm whales differ from modern sperm whales in tooth count and the shape of the face and jaws.
Two poorly known fossil species belonging to the modern genus Physeter have been recognized so far: P. antiquus (Neogene of France)[218] and P. vetus (Neogene of eastern North America).[219] Physeter vetus is very likely an invalid species, as the few teeth that were used to identify this species appear to be identical to those of another toothed whale, Orycterocetus quadratidens.[220]
Phylogeny
The traditional view has been that
These analyses also confirm that there was a rapid
Relationship with humans
Sperm whaling
Prior to the early eighteenth century, hunting was mostly by indigenous Indonesians.[227] Legend has it that sometime in the early 18th century, around 1712, Captain Christopher Hussey, while cruising for right whales near shore, was blown offshore by a northerly wind, where he encountered a sperm whale pod and killed one.[228] Although the story may not be true, sperm whales were indeed soon exploited by American whalers. Judge Paul Dudley, in his Essay upon the Natural History of Whales (1725), states that a certain Atkins, 10 or 12 years in the trade, was among the first to catch sperm whales sometime around 1720 off the New England coast.[229]
There were only a few recorded instances during the first few decades (1709–1730s) of offshore sperm whaling. Instead, sloops concentrated on the Nantucket Shoals, where they would have taken right whales or went to the Davis Strait region to catch bowhead whales. By the early 1740s, with the advent of spermaceti candles (before 1743), American vessels began to focus on sperm whales. The diary of Benjamin Bangs (1721–1769) shows that, along with the bumpkin sloop he sailed, he found three other sloops flensing sperm whales off the coast of North Carolina in late May 1743.[230] On returning to Nantucket in the summer 1744 on a subsequent voyage, he noted that "45 spermacetes are brought in here this day," another indication that American sperm whaling was in full swing.[230]
American sperm whaling soon spread from the east coast of the American colonies to the
The sperm whale's ivory-like teeth were often sought by 18th- and 19th-century whalers, who used them to produce inked carvings known as scrimshaw. 30 teeth of the sperm whale can be used for ivory. Each of these teeth, up to 20 cm (8 in) and 8 cm (3 in) across, are hollow for the first half of their length. Like walrus ivory, sperm whale ivory has two distinct layers. However, sperm whale ivory contains a much thicker inner layer. Though a widely practised art in the 19th century, scrimshaw using genuine sperm whale ivory declined substantially after the retirement of the whaling fleets in the 1880s.[citation needed]
Modern whaling was more efficient than open-boat whaling, employing steam-powered ships and exploding harpoons. Initially, modern whaling activity focused on large baleen whales, but as these populations were taken, sperm whaling increased. Spermaceti, the fine waxy oil produced by sperm whales, was in high demand. In both the 1941–1942 and 1942–1943 seasons, Norwegian expeditions took over 3,000 sperm whales off the coast of Peru alone. After World War II, whaling continued unabated to obtain oil for cosmetics and high-performance machinery, such as automobile transmissions.[citation needed]
The hunting led to the near-extinction of large whales, including sperm whales, until bans on whale oil use were instituted in 1972. The International Whaling Commission gave the species full protection in 1985, but hunting by Japan in the northern Pacific Ocean continued until 1988.[234]
It is estimated that the historic worldwide population numbered 1,100,000 before commercial sperm whaling began in the early 18th century.[3] By 1880, it had declined by an estimated 29 percent.[3] From that date until 1946, the population appears to have partially recovered as whaling activity decreased, but after the Second World War, the population declined even further, to 33 per cent of the pre-whaling population.[citation needed] Between 184,000 and 236,000 sperm whales were killed by the various whaling nations in the 19th century,[238] while in the 20th century, at least 770,000 were taken, the majority between 1946 and 1980.[239]
Sperm whales increase levels of primary production and carbon export by depositing iron-rich faeces into surface waters of the Southern Ocean. The iron-rich faeces cause phytoplankton to grow and take up more carbon from the atmosphere. When the phytoplankton dies, it sinks to the deep ocean and takes the atmospheric carbon with it. By reducing the abundance of sperm whales in the Southern Ocean, whaling has resulted in an extra 2 million tonnes of carbon remaining in the atmosphere each year.[240]
Remaining sperm whale populations are large enough that the species' conservation status is rated as vulnerable rather than endangered.
Current conservation status
The total number of sperm whales in the world is unknown, but is thought to be in the hundreds of thousands.[3] The conservation outlook is brighter than for many other whales. Commercial whaling has ceased,[3] and the species is protected almost worldwide, though records indicate that in the 11-year period starting from 2000, Japanese vessels have caught 51 sperm whales.[needs update] Fishermen do not target sperm whales to eat,[3] but long-line fishing operations in the Gulf of Alaska have complained about sperm whales stealing fish from their lines.[161]
Currently, entanglement in fishing nets and collisions with ships represent the greatest threats to the sperm whale population.
Sperm whales are listed on Appendix I
The species is protected under Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This makes commercial international trade (including in parts and derivatives) prohibited, with all other international trade strictly regulated through a system of permits and certificates.[4]
Cultural importance
Rope-mounted teeth are important cultural objects throughout the Pacific. In New Zealand, the Māori know them as "rei puta"; such whale tooth pendants were rare objects because sperm whales were not actively hunted in traditional Māori society.[245] Whale ivory and bone were taken from beached whales. In Fiji the teeth are known as tabua, traditionally given as gifts for atonement or esteem (called sevusevu), and were important in negotiations between rival chiefs.[246] Friedrich Ratzel in The History of Mankind reported in 1896 that, in Fiji, whales' or cachalots' teeth were the most-demanded article of ornament or value. They occurred often in necklaces.[247] Today the tabua remains an important item in Fijian life. The teeth were originally rare in Fiji and Tonga, which exported teeth, but with the Europeans' arrival, teeth flooded the market and this "currency" collapsed. The oversupply led in turn to the development of the European art of scrimshaw.[248]
In
The sperm whale was designated as the Connecticut state animal by the General Assembly in 1975.[252] It was selected because of its specific contribution to the state's history and because of its present-day plight as an endangered species.[253]
Watching sperm whales
Sperm whales are not the easiest of whales to watch, due to their long dive times and ability to travel long distances underwater. However, due to the distinctive look and large size of the whale, watching is increasingly popular.[citation needed] Sperm whale watchers often use hydrophones to listen to the clicks of the whales and locate them before they surface.[254] Popular locations for sperm whale watching include the town of Kaikōura on New Zealand's South Island, Andenes and Tromsø in Arctic Norway; as well as the Azores, where the continental shelf is so narrow that whales can be observed from the shore,[141][255] and Dominica[256] where a long-term scientific research program, The Dominica Sperm Whale Project, has been in operation since 2005.[257]
Plastic waste
The introduction of plastic waste to the ocean environment by humans is relatively new. From the 1970s, sperm whales have occasionally been found with pieces of plastic in their stomachs.[167][258][259][260]
See also
Notes
- ^ /ˈkæʃəlɒt, ˈkæʃəloʊ/ – "cachalot". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
References
- OCLC 62265494.
- ^ "Physeter macrocephalus Linnaeus 1758 (sperm whale)". Fossilworks: Gateway to the Paleobiology Database. Retrieved 17 December 2021.
- ^ . Retrieved 19 November 2021.
- ^ a b "Appendices | CITES". cites.org. Retrieved 14 January 2022.
- ^ "Sperm Whale". acsonline.org. Archived from the original on 22 April 2017. Retrieved 13 May 2017.
- ^ PMID 24670984.
- ^ a b "Census of Marine Life – From the Edge of Darkness to the Black Abyss" (PDF). Coml.org. Retrieved 15 December 2009.
- PMID 12942991.
- ^ Trivedi, Bijal P. (3 November 2003). "Sperm Whale "Voices" Used to Gauge Whales' Sizes". National Geographic. Archived from the original on 6 November 2003.
- ^ ISBN 978-0-691-12757-6.
- ^ ISBN 978-0-375-41141-0.
- ^ ISBN 978-0-226-50341-7.
- ^ Spitznagel, Eric (12 January 2012). "Ambergris, Treasure of the Deep". Bloomberg L.P. Retrieved 25 May 2017.
- PMID 16419786.
- JSTOR 983449.
- ^ Fеrnandez-Casado, M. (2000). "El Cachalote (Physeter macrocephalus)" (PDF). Galemys. 12 (2): 3. Archived from the original (PDF) on 7 August 2020. Retrieved 27 September 2013.
- ^
Corominas, Joan (1987). Breve diccionario etimológico de la lengua castellana. Madrid: Gredos. ISBN 978-84-249-1332-8.
- ^ Encarta Dictionary
- ^ Crabb, George (1823). Universal Technological Dictionary Or Familiar Explanation of the Terms Used in All Arts and Sciences: Containing Definitions Drawn from the Original Writers : in Two Volumes. Baldwin, Cradock & Joy. p. 333.
- ISBN 978-0-12-588504-1.
The earliest available species-group name for a Southern Hemisphere sperm whale is Physeter australasianus Desmoulins, 1822.
- . The Insomniac Society.
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: CS1 maint: numeric names: authors list (link)
Further reading
- Whitehead, H. (2003). Sperm Whales: Social Evolution in the Ocean. Chicago: University of Chicago Press. p. 4. ISBN 978-0-226-89518-5.
- Perrin, William F.; Würsig, Bernd; Thewissen, J.G.M., eds. (2002). Encyclopedia of Marine Mammals. San Diego, Calif.: Academic Press. ISBN 978-0-12-551340-1.
- Carwardine, Hoyt; Fordyce & Gill (1998). Whales & Dolphins: The Ultimate Guide to Marine Mammals. London: HarperCollins. ISBN 978-0-00-220105-6.
- Heptner, V. G.; Nasimovich, A. A; Bannikov, Andrei Grigorevich; Hoffmann, Robert S, Mammals of the Soviet Union, Volume II, part 3 (1996). Washington, D.C.: Smithsonian Institution Libraries and National Science Foundation
External links
- The Dominica Sperm Whale Project- a long-term scientific research program focusing on the behaviour of sperm whale units.
- Spermaceti in candles 22 July 2007
- Society for Marine Mammalogy Sperm Whale Fact Sheet
- US National Marine Fisheries Service Sperm Whale web page
- 70South—information on the sperm whale
- "Physty"-stranded sperm whale nursed back to health and released in 1981
- ARKive—Photographs, video.
- Whale Trackers—An online documentary film exploring the sperm whales in the Mediterranean Sea.
- Convention on Migratory Species page on the sperm whale
- Website of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region
- Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
- Retroposon analysis of major cetacean lineages: The monophyly of toothed whales and the paraphyly of river dolphins 19 June 2001
- Voices in the Sea – sounds of the sperm whale
- Sperm whales quickly learned to avoid humans who were hunting them in the 19th century, scientists say. ABC News. 16 March 2021.