The sperm whale is the largest toothed whale, with adult males measuring up to long and weighing up to . By contrast, the second largest toothed whale (Baird's beaked whale) measures and weighs up to . The sperm whale is among the most sexually dimorphic of all cetaceans. At birth both sexes are about the same size, but mature males are typically 30% to 50% longer and three times as massive as females. Newborn sperm whales are usually between long in length. Female sperm whales are physically mature at about in length and generally don't grow much larger than about .
External appearance
Sperm whale
Sperm whale | External appearance
It is distinguished by its large tooth. The sperm whale is the largest toothed whale and at birth both sexes are about the same size, but mature males are typically 30% to 50% longer and three times as massive as females. The sperm whale is the largest toothed whale. At birth both sexes are about the same size, but mature males are typically 30% to 50% longer and three times as massive as females.
what ocean zone does the sperm whale live in
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They are relatively abundant from the poles to the equator and are found in all the oceans.
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where does this whale species get its name from?
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It is a truncation of "spermaceti whale".
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what does it look like?
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The sperm whale is the largest toothed whale, with adult males measuring up to long and weighing up to . By contrast, the second largest toothed whale (Baird's beaked whale) measures and weighs up to . The sperm whale is among the most sexually dimorphic of all cetaceans. At birth both sexes are about the same size, but mature males are typically 30% to 50% longer and three times as massive as females. Newborn sperm whales are usually between long in length. Female sperm whales are physically mature at about in length and generally don't grow much larger than about .
Sperm whale | External appearance
The term is retained in the Russian word for the animal, (""), as well as in many other languages. The scientific genus name "Physeter" comes from the Greek "" (), meaning "blowpipe, blowhole (of a whale)", or – as a "pars pro toto" – "whale". The specific name "macrocephalus" is Latinized from the Greek ' (, meaning "big-headed"), from ' (, "large") + "" (, "head"). Its synonymous specific name "catodon" means "down-tooth", from the Greek elements ' ("below") and ' ("tooth"); so named because it has visible teeth only in its lower jaw. (See: Teeth) Another synonym "australasianus" ("Australasian") was applied to sperm whales in the Southern Hemisphere.
Sperm whale | Etymology
In 1853, one sperm whale was reported at in length with a head measuring .
Sperm whale | External appearance
The males of most species are covered in scars from the teeth of other males. The lower jaw often forms a huge arch in some species, sometimes extending above the rostrum in a shape comparable to a playground slide. Every species has large (sometimes tusk-like) teeth of variable size, shape, and position.
Mesoplodont whale | Physical description
The right nasal passage was small and was asymmetrical with the left nasal passage, like in the modern sperm whale. Characteristic of sperm whales, it had a deep basin on the top of its skull, known as the supracranial basin. Like in the modern sperm whale, this basin probably held the spermaceti organ, and so the whale had biosonar capabilities. The nuchal crest which is the part of the whale skull which projects upwards on the back end of the skull, behind the supracranial basin, was low and broad. Similar to modern-day toothed whales, but unlike in the modern sperm whale, the shoulder blades were thicker than they were taller.
Brygmophyseter | Description
The name "sperm whale" is a truncation of "spermaceti whale". Spermaceti, originally mistakenly identified as the whales' semen, is the semi-liquid, waxy substance found within the whale's head (see 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 ' 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 ', plural of "", "sword hilt". The word "cachalot" came to English via French from Spanish or Portuguese ', perhaps from Galician/Portuguese ', "big head".
Sperm whale | Etymology
The sperm whale characteristically has a large, squarish head one-third the length of its body; the blowhole is slightly to the left hand side; the skin is usually wrinkled; and it has no teeth on the upper jaw.
List of cetaceans | Family Physeteridae: sperm whale
The pygmy sperm whale is not much larger than many dolphins. They are about at birth, growing to about at maturity. Adults weigh about . The underside is a creamy, occasionally pinkish colour and the back and sides are a bluish grey; however, considerable intermixing occurs between the two colours. The shark-like head is large in comparison to body size, given an almost swollen appearance when viewed from the side. A whitish marking, often described as a "false gill", is seen behind each eye. The lower jaw is very small and slung low. The blowhole is displaced slightly to the left when viewed from above facing forward.
Pygmy sperm whale | Description
Its appearance resembles the larger fin whale (thus the alternate common names of dwarf fin whale and little fin whale), both having a dark gray left lower jaw, and on the right side a white mandible patch, a white blaze, a dark eye stripe, a white inter-stripe wash, as well as a white chevron on the back, pectoral fins with a white anterior border and inner surface, and flukes with a white ventral surface and black margins. Like fin whales, it also exhibits a white left gape and a dark right gape, a reversal of the asymmetrical pigmentation on the lower jaw.
Omura's whale | External appearance
Male sperm whales are physically mature at about in length and generally reaching a maximum of about . There are old reports of sperm whales approaching, reaching or exceeding in length but there is disagreement as to the accuracy of these claims which are often considered exaggerations or as being measured along the curves of the body. The whale that sank the "Essex" (one of the incidents behind "Moby-Dick") was claimed to be . The Nantucket Whaling Museum has a -long jawbone which the museum claims that this individual was long. A long jawbone is held in the British Natural History Museum and a long jawbone is held in the Oxford University Museum of Natural History.
Sperm whale | External appearance
Some individuals have been known to have a second crescent-shaped mark, creating a sort of pale ring encircling a darker spot. It has a high dorsal fin halfway down the length of the body, and two or more throat grooves. The dorsal fin is taller and closer to the head than it is in the pygmy sperm whale, and the back is flatter. "Kogia" is identified as having a square head, a small jaw with the snout jutting outward, and a porpoise-like build with a robust body that rapidly decreases towards the tail. They have the shortest snouts of any modern day whale.
Dwarf sperm whale | Description
Like its giant relative, the sperm whale, the pygmy sperm whale has a spermaceti organ in its forehead (see sperm whale for a discussion of its purpose). It also has a sac in its intestines that contains a dark red fluid. The whale may expel this fluid when frightened, perhaps to confuse and disorient predators. Dwarf and pygmy sperm whales possess the shortest rostrum of current day cetaceans with a skull that is greatly asymmetrical Pygmy sperm whales have from 50 to 55 vertebrae, and from 12 to 14 ribs on either side, although the latter are not necessarily symmetrical, and the hindmost ribs do not connect with the vertebral column.
Pygmy sperm whale | Anatomy
Characteristic of sperm whales, the left nostril is markedly larger than the right, and it has a spermaceti organ on its skull. The brain weighs around . The eyes are adapted for low-light environments. The dwarf sperm whale has 14 to 24 teeth, rarely 26, in the lower jaw that are sharp, slightly curved backwards, and–like other sperm whales–lack enamel. The teeth rarely exceed in length, smaller than those of the pygmy sperm whale. At most, 6 teeth are in the upper jaws, though in modern sperm whales, upper teeth are defunct. Unique to "Kogia", there is a sac which hangs off from the small intestines near the anus that is filled with a dense, red-brown fluid that looks similar to chocolate syrup.
Dwarf sperm whale | Description
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. "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. "Placoziphius", found in Europe, and "Acrophyseter", from Peru, are dated to the late Miocene. Fossil sperm whales differ from modern sperm whales in tooth count and the shape of the face and jaws. For example, "Scaldicetus" had a tapered rostrum. Genera from the Oligocene and early and middle Miocene, with the possible exception of "Aulophyseter", had teeth in their upper jaws.
Sperm whale | Fossil record
Like in other macroraptorial sperm whales, tooth size increased from the back of the jaw to the front. The maximum diameter of the crown (the part of the tooth that is visible and erupts from the gum line) ranges from , and diameter was greatest midway up the tooth.
Scaldicetus | Tooth anatomy
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, which the sperm whale uses for echolocation and communication. 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 litres of spermaceti. It is proportionately larger in males. This oil is a mixture of triglycerides and wax esters. The proportion of wax esters in the spermaceti organ increases with the age of the whale: 38–51% in calves, 58–87% in adult females, and 71–94% in adult males.
Sperm whale | Spermaceti organ and melon
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. The fin whale ("Balaenoptera physalus") has complex and asymmetrical coloration on its head.
List of animals featuring external asymmetry | Mammals
These evolutionary modifications make the spine more flexible but weaker than the spines of terrestrial vertebrates. 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. 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.
Sperm whale | Skeleton
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. 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.
Sperm whale | Mechanism
The analogous structure in the sperm whale is traditionally called "the junk" because whalers dismissed it as a worthless source of sperm oil. It contains compartments of spermaceti separated by walls of cartilage.
Melon (cetacean) | Sperm whale
Unlike the modern sperm whale which only has teeth on the bottom jaw, "Scaldicetus" had teeth in both jaws. The lectotype for "S. caretti" had at least 45 teeth in total in its mouth in life. Like other macroraptorial sperm whales but unlike the modern sperm whale, the teeth were covered in a thick enamel coating, about thick. The teeth were moderately curved and were deeply rooted into the skull, implying a strong bite. Like in other sperm whales, tooth dimensions vary widely; for the lectotype: the total length of the tooth root (the part of the tooth beneath the gum line) is between and the maximum total length of the entire tooth is .
Scaldicetus | Tooth anatomy
Unlike in the modern sperm whale, the premaxillae reached the sides of the snout. The upper jaw was thick, especially midway through the snout. The snout was asymmetrical, with the right maxilla in the upper jaw becoming slightly convex towards the back of the snout, and the left maxilla becoming slightly concave towards the back of the snout. The vomer reached the tip of the snout, and was slightly concave, decreasing in thickness from the back to the front. A sudden thickening in the middle-left side of the vomer may indicate the location of the nose plug muscles. Each mandible in the lower jaw was higher than it was wide, with a larger gap in between the two than in the modern sperm whale.
Livyatan | Skull
The dwarf and pygmy sperm whales resemble sperm whales, but are far smaller. They have blunt, squarish heads with narrow, underslung jaws; the flippers are set far forward, close to the head and their dorsal fins are set far back down the body. They c
List of cetaceans | Family Kogiidae: dwarf and pygmy sperm whales
Orycteocetus is an extinct genus of sperm whale from the Miocene of the northern Atlantic Ocean.
Orycterocetus | Introduction
Spout shapes differ among species, which facilitates identification.
Whale | Anatomy
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, but are unable to roll the eyes in their sockets.
Sperm whale | Eyes and vision
It has a very falcate dorsal fin with a leading edge that gradually slopes into the back, halfway in shape between the more gradual slope of the fin whale and the more acute angle of Bryde's and sei whales. Its dorsal fin is also proportionally smaller and less upright than these other species. It typically has a single prominent median ridge on the rostrum, but can have faint lateral ridges, which are more pronounced in calves. Bryde's whale, on the other hand, has three prominent ridges on the rostrum. It has 45 to 95 ventral grooves that extend past the umbilicus.
Omura's whale | External appearance
"Orycterocetus" is a member of Physeteroidea closely related to crown-group sperm whales. The type species, "O. quadratidens", was first named by Joseph Leidy on the basis of two teeth, two partial mandibular rami, and a rib from Neogene deposits of Virginia. Two more species were subsequently described, "O. cornutidens" Leidy 1856 and "O. crocodilinus" Cope, 1868, the latter from the middle Miocene Calvert Formation.
Orycterocetus | Classification
Sexual dimorphism is also displayed through whale song, notably in humpback whales where the males of the species sing elaborate songs. Male right whales have bigger callosities than female right whales. The males are generally more scarred than females which is thought to be because of aggression during mating season.
Baleen whale | External anatomy
The 40 to 70 ventral pleats extend to or past the umbilicus, occupying about 58% and 57% of the total length, respectively; sei whales, though, have ventral pleats that extend only halfway between the pectoral fins and umbilicus, occupying only 45–47% of the total body length, whereas their umbilicus is usually 52% of the total body length. Both species are often covered with white or pink oval scars caused by bites from cookie-cutter sharks.
Bryde's whale | External appearance
The sperm whale ("Physeter macrocephalus") is the largest species of toothed whale, with adult bulls (males) growing to be about long, and weighing about . The two kogiid species are much smaller, around in length, and weighing . The bodies of physeteroids are robustly proportioned, with paddle-shaped flippers. The lower jaw is always relatively small and thin relative to the upper jaw. The nasal bones of these whales are distinctly asymmetrical, with the blowhole being located on the left side of the head; in the sperm whale, this is near the top of the head, while on the kogiids it is further forward.
Physeteroidea | Characteristics
Like in other sperm whales, the blowhole was slanted towards the left side of the animal, and it may have lacked a right nasal passage. The falciform process on the squamosal bone was large and ventrally facing; as opposed to the ones in the Kogiidae ("Kogia" and "Praekogia") which are either reduced or absent. These may have been reduced in kogiids due to adaptations to deep-sea diving. Like in modern sperm whales, "Zygophyseter" had a very large basin above the braincase, known as the supracranial basin, which probably housed the spermaceti organ and the melon. These are used in the generation and focusing of sound for biosonar in the modern sperm whale, indicating "Zygophyseter" had some mechanisms for biosonar; that is to say this animal could have used echolocation.
Zygophyseter | Skull
The sperm whale belongs to the order Cetartiodactyla, 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. In some taxonomic schemes the families Kogiidae and Physeteridae are combined as the superfamily Physeteroidea (see the separate entry on the sperm whale family).
Sperm whale | Taxonomy
Analyzing the teeth is the preferred method for determining a whale's age. Like the age-rings in a tree, the teeth build distinct layers of cementum and dentine as they grow.
Sperm whale | Jaws and teeth
Note that the view pictured on the right is an axial view, not coronal as noted
Pygmy sperm whale | Melon
"Scaldicetus" is known from the Miocene to Pleistocene deposits of Western Europe, the U.S. (California, Florida, Maryland, Virginia), Baja Peninsula, Peru, New South Wales, and Japan. However, "Scaldicetus" is probably a grade taxon, and fossil teeth assigned to it (largely due to the lack of distinguishing characteristics in fossil teeth alone) probably represent more-or-less unrelated sperm whales united by their primitive characteristics rather than actual ancestry. Consequently, this would inflate the genus's distribution. The name "Scaldicetus caretti" was coined in 1867 from numerous sperm whale teeth collected in Neogene deposits near Antwerp, Belgium probably from the early-to-middle Miocene Bercham Formation.
Scaldicetus | Taxonomy
Whales have torpedo shaped bodies with non-flexible necks, limbs modified into flippers, non-existent external ear flaps, a large tail fin, and flat heads (with the exception of monodontids and ziphiids). Whale skulls have small eye orbits, long snouts (with the exception of monodontids and ziphiids) and eyes placed on the sides of its head. Whales range in size from the and dwarf sperm whale to the and blue whale. Overall, they tend to dwarf other cetartiodactyls; the blue whale is the largest creature on earth. Several species have female-biased sexual dimorphism, with the females being larger than the males. One exception is with the sperm whale, which has males larger than the females.
Whale | Anatomy
The traditional view has been that Mysticeti (baleen whales) and Odontoceti (toothed whales) arose from more primitive whales early in the Oligocene period, and that the super-family Physeteroidea, which contains the sperm whale, dwarf sperm whale, and pygmy sperm whale, diverged from other toothed whales soon after that, over . From 1993 to 1996, molecular phylogenetics analyses by Milinkovitch and colleagues, based on comparing the genes of various modern whales, suggested that the sperm whales are more closely related to the baleen whales than they are to other toothed whales, which would have meant that Odontoceti were not monophyletic; in other words, it did not consist of a single ancestral toothed whale species and all its descendants.
Sperm whale | Phylogeny
The sperm whale, or common cachalot, is a large toothed whale belonging to the infraorder Cetacea. Cachalot may also refer to:
Cachalot (disambiguation) | Introduction
The sperm whale or cachalot ("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". The sperm whale is a pelagic mammal with a worldwide range, and will migrate seasonally for feeding and breeding. 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.
Sperm whale | Introduction
The spermaceti organ is an organ that commonly appears in the heads of toothed whales of the family Physeteroidea, in particular the sperm whale. This organ contains a waxy liquid called spermaceti and is involved in the generation of sound. In the modern sperm whale ("Physeter macrocephalus"), the spermaceti organ is far larger in proportion to the animal’s body than what would be explained by simple allometry, and the evolution of the organ has caused changes in basal skull morphology, which may implicate tradeoffs were made that compromised the functionality of other nearby features. The high investment in this organ suggests that the organ must have adaptively advantageous functionality.
Spermaceti organ | Introduction
"Zygophyseter" was discovered in the Pietra Leccese Formation in Italy from a skull, teeth, and vertebrae; "Brygmophyseter" was discovered in the Bessho Formation in Japan from a nearly-complete skeleton; and "Acrophyseter" and "Livyatan" both originate from the Pisco Formation in Peru and are known by only a skull. It has also been suggested that the macroraptorials be placed into the subfamily Hoplocetinae, a subfamily characterized by robust and enamel-coated teeth, alongside the genera "Diaphorocetus", "Idiorophus", and "Hoplocetus", which are known from the Miocene to the Early Pleistocene. However, most of these whales are known from fragmentary remains or have been used as wastebasket taxa for indiscernible stem sperm whale remains.
Macroraptorial sperm whale | Taxonomy
The braincase is concentrated through the nasal passage to the front and is correspondingly higher, with individual cranial bones that overlap. In toothed whales, connective tissue exists in the melon as a head buckle. This is filled with air sacs and fat that aid in buoyancy and biosonar. The sperm whale has a particularly pronounced melon; this is called the spermaceti organ and contains the eponymous spermaceti, hence the name "sperm whale". Even the long tusk of the narwhal is a vice-formed tooth. In many toothed whales, the depression in their skull is due to the formation of a large melon and multiple, asymmetric air bags.
Cetacea | Head
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. 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". 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.
Sperm whale | Taxonomy
The dwarf sperm whale ("Kogia sima") is a sperm whale that inhabits temperate and tropical oceans worldwide, in particular continental shelves and slopes. It was first described by biologist Richard Owen in 1866, based on illustrations by naturalist Sir Walter Elliot. The species was considered to be synonymous with the pygmy sperm whale ("Kogia breviceps") from 1878 until 1998. The dwarf sperm whale is a small whale, and , that has a gray coloration, square head, small jaw, and robust body. Its appearance is very similar to the pygmy sperm whale, distinguished mainly by the position of the dorsal fin on the body–nearer the middle in the dwarf sperm whale and nearer the back in the other.
Dwarf sperm whale | Introduction
The total population is unknown. Fossils identified as belonging to "K. breviceps" have been recovered from Miocene deposits in Italy, Japan, and southern Africa.
Pygmy sperm whale | Population and distribution
The holotype was recovered from an unspecified location in the sea cliffs near the original Santa Barbara Lighthouse in 1909, which is believed to most likely be part of the Monterey Formation. The whale was originally placed in the genus "Ontocetus" in 1925 by American naturalist Remington Kellogg as "O. oxymycterus". This genus was originally thought to represent a sperm whale, however, in 2008, the type species, "Ontocetus emmonsi", was discovered to actually be a walrus. The whale was then moved to the wastebasket taxon "Scaldicetus", which consists of various other (more-or-less unrelated) primitive sperm whales with enamel coated teeth.
Albicetus | Taxonomic history
deinodon". The genus name "Acrophyseter" is derived from the Greek –meaning acute, which describes the short, pointed, upturned snout–and –which is the genus name for the modern sperm whale "Physeter macrocephalus". The species name "deinodon" is from the Greek –meaning terrible–and –tooth.
Acrophyseter | Taxonomy
This back and forth reflection which happens on the scale of a few milliseconds creates a multi-pulse click structure. This multi-pulse click structure allows researchers to measure the whale's spermaceti organ using only the sound of its clicks. 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. The lower jaw is the primary reception path for the echoes.
Sperm whale | Mechanism
The dorsal fin is very small and hooked; its size is considerably smaller than that of the dwarf sperm whale and may be used for diagnostic purposes.
Pygmy sperm whale | Description
The large teeth of the raptorial sperm whales either evolved once in the group with a basilosaurid-like common ancestor, or independently in "Livyatan". The large temporal fossa in the skull of raptorial sperm whales is thought to a plesiomorphic feature, that is, a trait inherited from a common ancestor. Since the teeth of foetal modern sperm whales ("Physeter macrocephalus") have enamel on them before being coated with cementum, it is thought that the enamel is also an ancient characteristic (basal). The appearance of raptorial sperm whales in the fossil record coincides with the diversification of baleen whales in the Miocene, implying that they evolved specifically to exploit baleen whales.
Livyatan | Phylogeny
They use a suction technique, aided by a pair of grooves on the underside of their head, not unlike the throat pleats on the rorquals, to feed.
Whale | Odontocetes
Spermaceti (from Greek "sperma" meaning "seed", and "ceti", the genitive form of "whale") is a waxy substance found in the head cavities of the sperm whale (and, in smaller quantities, in the oils of other whales). Spermaceti is created in the spermaceti organ inside the whale's head. This organ may contain as much as of spermaceti. Two theories for the spermaceti organ's biological function suggest it either controls buoyancy, or acts as a focusing apparatus for the whale's sense of echolocation. There has been concrete evidence to support both theories. The buoyancy theory holds that the sperm whale is capable of heating the spermaceti, lowering its density and thus allowing the whale to float; in order for the whale to sink again, it must take water into its blowhole which cools the spermaceti into a denser solid.
Spermaceti | Introduction
The postcranial remains of only "Zygophyseter" and "Brygmophyseter" were found. The elongated lumbar vertebrae of "Zygophyseter" indicate it had larger multifidus and longissimus back muscles and was, thus, faster than the modern sperm whale which, comparable to other large open-ocean animals, travels horizontally at . A characteristic of sperm whales, the macroraptorials had a curved basin–the supracranial basin–on the top of the skull. This encompassed the entire breadth if the snout in "Livyatan" and "Brygmophyseter"; "Zygophyseter" and "Acrophyseter", instead, had reduced basins indicating beaks.
Macroraptorial sperm whale | Description
However, more recent studies, based on various combinations of comparative anatomy and molecular phylogenetics, criticised Milinkovitch's analysis on technical grounds and reaffirmed that the Odontoceti are monophyletic. These analyses also confirm that there was a rapid evolutionary radiation (diversification) of the Physeteroidea in the Miocene period. The Kogiidae (dwarf and pygmy sperm whales) diverged from the Physeteridae (true sperm whales) at least .
Sperm whale | Phylogeny
"Acrophyseter", from the late Miocene, also had teeth in both the upper and lower jaws as well as a short rostrum and an upward curving mandible (lower jaw). These anatomical differences suggest that fossil species may not have necessarily been deep-sea squid eaters such as the modern sperm whale, but that some genera mainly ate fish. "Zygophyseter", dated from the middle to late Miocene and found in southern Italy, had teeth in both jaws and appears to have been adapted to feed on large prey, rather like the modern killer whale (orca). Other fossil sperm whales with adaptations similar to this are collectively known as killer sperm whales.
Sperm whale | Fossil record
The first two dwarf sperm whale specimens, a male and a female, were collected in 1853 by naturalist Sir Walter Elliot, who thought it a kind of porpoise due to the short snout. However, when he sent drawings of these whales–including skeletal diagrams–to biologist Richard Owen to describe, Owen, in his 1866 paper, recognized it as a type of sperm whale in the family Physeteridae based on several similar characteristics, such as having functional teeth in only the lower jaw, a lopsided blowhole leaning towards the left side, and a spermaceti organ. He named it "Physeter (Euphysetes) simus", the same genus as the sperm whale ("Physeter macrocephalus") and the pygmy sperm whale (now "Kogia breviceps"), with "Euphysetes" acting as a subgenus.
Dwarf sperm whale | Taxonomy
The head of "Janjucetus" is similar to the wide and blunt heads of modern-day, suction-feeding toothed whales, indicating it could suction feed.
Janjucetus | Palaeoecology
pusilla" has a basin formed by the right premaxilla, which, in modern "Kogia", houses the spermaceti organ. The organ is unique to sperm whales and aids in echolocation by focusing sound. Due to the less-pronounced cheekbones, the anterior cranial fossa–depressions on the skull–are smaller than in modern "Kogia". The lacrimal bone is hooked-shape like in Physeteridae in contrast to the triangular lacrimal bone of Kogiidae. Like other kogiids, it does not have nasal bones. Thinking it was a beaked whale and using the holotype of "Placoziphius" for scale, Capellini estimated the length at .
Kogia pusilla | Description
Although the fossil record is poor, 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". "Ferecetotherium", found in Azerbaijan and dated to the late Oligocene (about ), is the most primitive fossil that has been found, which possesses sperm whale-specific features, such as an asymmetric rostrum ("beak" or "snout"). Most sperm whale fossils date from the Miocene period, . "Diaphorocetus", from Argentina, has been dated to the early Miocene.
Sperm whale | Fossil record
There is sometimes a dark blaze between the head and dorsal fin as well. One female in the Southern Hemisphere was bluish black with a white area between the dorsal fin and tail as well as a light gray jaw and throat, as well as black speckling. One individual from the Canary Islands had an area of white from snout to blowhole. Scars from fighting and cookiecutter sharks are present on males. This species reaches around with the females weighing and the males weighing . They are around long when born.
True's beaked whale | Physical description
The spermaceti at the core of the organ has a higher wax content than the outer areas. The speed of sound in spermaceti is 2,684 m/s (at 40 kHz, 36 °C), making it nearly twice as fast as in the oil in a dolphin's melon. Below the spermaceti organ lies the "junk" which consists of compartments of spermaceti separated by cartilage. It is analogous to the melon found in other toothed whales. The structure of the junk redistributes physical stress across the skull and may have evolved to protect the head during ramming.
Sperm whale | Spermaceti organ and melon
Two fossil species belonging to the modern genus "Physeter" have been recognized so far: "P. antiquus" (Neogene of France) and "P. vetus" (Neogene of eastern North America).
Sperm whale | Fossil record
However, due to a poor fossil record of "Livyatan", collecting bias is another possible explanation. The holotype of "L. melvillei" is from the Tortonian stage of the Upper Miocene 9.9–8.9 mya in the Pisco Formation of Peru, which is known for its well-preserved assemblage of marine vertebrates. Among the baleen whales found, the most common was an undescribed species of cetotheriid whale measuring around , and most of the other baleen whales found were roughly the same size. Toothed whale remains found consist of beaked whales (such as "Messapicetus gregarius"), ancient pontoporiids (such as "Brachydelphis mazeasi"), oceanic dolphins, and the raptorial sperm whale "Acrophyseter".
Livyatan | Palaeoecology
Sperm whales have 21 pairs of chromosomes (2n=42). The genome of live whales can be examined by recovering shed skin.
Sperm whale | Genetics
It is distinguished from the other raptorial sperm whales by the basin on the skull, and how it spans the entire length of the snout. The spermaceti organ, contained in that basin, is thought to have been used in echolocation and communication, or for ramming prey and other sperm whales. The whale may have interacted with the large extinct shark megalodon ("Otodus megalodon"), competing with it for a similar food source. Its extinction was likely caused by a cooling event at the end of the Miocene which resulted in a drop in food populations. The formation where the whale has been found has also preserved a large assemblage of marine life, such as sharks and marine mammals.
Livyatan | Introduction
The pygmy sperm whale was first described by naturalist Henri Marie Ducrotay de Blainville in 1838. He based this on the head of an individual washed up on the coasts of Audierne in France in 1784, which was then stored in the Muséum d'histoire naturelle. He recognized it as a type of sperm whale and assigned it to the same genus as the sperm whale ("Physeter macrocephalus") as "Physeter breviceps". He noted its small size and nicknamed it ""cachalot a tête courte""–small-headed sperm whale; further, the species name "breviceps" is Latin for "short-headed". In 1846, zoologist John Edward Gray erected the genus "Kogia" for the pygmy sperm whale as "Kogia breviceps", and said it was intermediate between the sperm whale and dolphins.
Pygmy sperm whale | Taxonomy
In the pygmy sperm whale ("Kogia breviceps"), the melon consists of an outer layer and an inner core. The inner core has a generally larger proportion of wax esters than the outer layer. Behind the melon is a cornucopia-shaped organ that many scientists refer to as the "spermaceti organ". This organ is different in form and composition from the spermaceti organ of the sperm whale.
Melon (cetacean) | Pygmy sperm whale
The sperm whale's lower jaw is very narrow and underslung. The sperm whale has 18 to 26 teeth on each side of its lower jaw which fit into sockets in the upper jaw. The teeth are cone-shaped and weigh up to each. The teeth are functional, but do not appear to be necessary for capturing or eating squid, as well-fed animals have been found without teeth or even with deformed jaws. One hypothesis is that the teeth are used in aggression between males. Mature males often show scars which seem to be caused by the teeth. Rudimentary teeth are also present in the upper jaw, but these rarely emerge into the mouth.
Sperm whale | Jaws and teeth
The dwarf sperm whale can range in size from in length and in weight—less than the and pygmy sperm whale. A newborn is generally around long and . Males are thought to reach physical maturity at age 15, and females age 13. Sexual maturity, which happens after an individual has attained in length, happens at 2 to 3 years for males and around 5 for females. Gestation takes place probably over around 9.5 months. The dwarf sperm whale has a dark-gray or blue-gray coloration with a lighter-gray underside, and a pale, crescent-shaped mark between the eye and the flipper, sometimes called a "fake gill," which is characteristic of the genus.
Dwarf sperm whale | Description
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.
Sperm whale | Brain
Livyatan is an extinct genus of sperm whale containing one species: L. melvillei. The genus name was inspired by the biblical sea monster Leviathan, and the species name by Herman Melville, the author of the famous book "Moby-Dick" about a white bull sperm whale. It is mainly known from the Pisco Formation of Peru during the Tortonian stage of the Miocene epoch, about 9.9–8.9 million years ago (mya); however, isolated teeth from other locations such as Chile, Argentina, South Africa, and Australia implies that either it or a close relative survived into the Pliocene, around 5mya, and was present throughout the Southern Hemisphere.
Livyatan | Introduction
Males also have a strong pair of teeth protruding from the mandibular symphysis.
Hubbs' beaked whale | Description
Toothed whales have torpedo-shaped bodies with inflexible necks, limbs modified into flippers, nonexistent external ear flaps, a large tail fin, and bulbous heads (with the exception of sperm whales). Their skulls have small eye orbits, long beaks (with the exception sperm whales), and eyes placed on the sides of their heads. Toothed whales range in size from the and vaquita to the and sperm whale. Overall, they tend to be dwarfed by their relatives, the baleen whales (Mysticeti). Several species have sexual dimorphism, with the females being larger than the males. One exception is with the sperm whale, which has males larger than the females.
Toothed whale | Anatomy
The pygmy sperm whale ("Kogia breviceps") is one of two extant species in the family Kogiidae in the sperm whale superfamily. They are not often sighted at sea, and most of what is known about them comes from the examination of stranded specimens.
Pygmy sperm whale | Introduction
Another theory says that the enlarged forehead caused by the presence of the spermaceti organ is used in all sperm whales between males fighting for females during mating season by head-butting each other, including "Livyatan" and the modern sperm whale. It may have also been used to ram into prey; if this is the case, in support of this, there have been two reports of modern sperm whales attacking whaling vessels by ramming into them, and the organ is disproportionally larger in male modern sperm whales. An alternate theory is that sperm whales, including "Livyatan", can alter the temperature of the wax in the organ to aid in buoyancy.
Livyatan | Spermaceti organ
Each whale's head held up to a ton, in a cavity called the "case". It was part of a waxy liquid called spermaceti, from which the whale got its common name. The liquid was removed from the spermaceti organ at sea, and stored separately from the rendered whale oil for processing back in port. On return home, this headmatter, which was worth around 20% more than the oil from the blubber, was divided into two valuable commodities. One was a very pure type of sperm whale oil that required little or no additional processing. It was found particularly suitable as a lubricant for fine machinery, such as pocket watches.
Sperm whaling | Economic motivation
The type specimen, USNM 10923, consists of a partial skull (mainly remains of the beak) and isolated tooth fragments. The total body size–extrapolated by comparing the occipital condyle length with antorbital notch (slits in the skull right before the snout) width of other primitive sperm whale–is estimated to be between . The preserved length of the beak is . The whale had a maximum of 18 teeth in either jaw, deeply rooted in exceedingly large tooth sockets.
Albicetus | Description
"K. pusilla" is differentiated from the dwarf and pygmy sperm whales by its more elongated snout, smaller lacrimal bone, less pronounced cheekbones, less elevation of the back top side of the skull, and more asymmetry between the left and right sides of the skull. It is smaller than the pygmy sperm whale and has a narrower sagittal crest along the mid-line of the skull. The blowhole is displaced even farther to the left than in modern-day "Kogia" and the sagittal crest more to the right. However, the skull size is comparable to that of the dwarf sperm whale. The braincase of "K.
Kogia pusilla | Description
Its length was estimated to be between .
Cryptid whale | High-finned sperm whale
Its flippers are small and tapered and its tail is wide, pointed at the tip, and notched in the centre. When the whale surfaces, the dorsal fin is visible soon after the spout. The spout is vertical and narrow and can reach heights of or more.
Fin whale | Colouration and markings
Both species have a sac in the lower portion of their intestinal tracts that contains up to 12 liters of dark reddish-brown fluid, which can be ejected to confuse or discourage potential predators.
Pygmy sperm whale | Diet/foraging behavior
The large teeth either evolved once in the group with a basilosaurid-like common ancestor, or independently in "Livyatan". The large temporal fossa depressions on the skull of raptorials is probably descended from a common ancestor (plesiomorphy). The presence of enamel is thought to be an ancient and basal characteristic, as it is present on the teeth of fetal modern sperm whales. Macroraptorials appeared during an adaptive radiation event of baleen whales in the Miocene, an increase in whale populations and diversity, implying the macroraptorials evolved specifically to exploit baleen whales. A tooth found in Australia indicates macroraptorials still existed 5 mya in the Pliocene.
Macroraptorial sperm whale | Taxonomy
Females are considerably larger than males. At birth, a calf typically measures in length.
Sei whale | Description
Bryde's have a straight rostrum with three longitudinal ridges that extend from the blowholes, where the auxiliary ridges begin as depressions, to the tip of the rostrum. The sei whale, like other rorquals, has a single median ridge, as well as a slightly arched rostrum, which is accentuated at the tip. Bryde's usually have dark grey lower jaws, whereas sei whales are lighter grey. Bryde's have 250–370 pairs of short, slate grey baleen plates with long, coarse, lighter grey or white bristles that are long by wide, while sei whales have longer, black or dark grey baleen plates with short, curling, wool-like bristles.
Bryde's whale | External appearance
Named after their whale-shaped body (from the Greek "ketos" meaning "whale" or "sea monster", "mimos" meaning "imitative" and the Latin "forma" meaning "form"), the Cetomimiformes have extremely large mouths and highly distensible stomachs. Their eyes are very small or vestigial; the lateral line (composed of huge, hollow tubes) is consequently very well developed to compensate for life in the pitch black depths. The dorsal and anal fins are set far back; all fins lack spines. The swim bladder is also absent, except in the larvae and juveniles which occur in the surface waters. Whalefish coloration is typically red to orange, sometimes with a black body.
Cetomimiformes | Description
The earliest sperm whale fossils are known from the late Oligocene – about 25 million years ago, with an ancestry tracing back from the latest Eocene before diverging from the remainder of the odontocetid line, leading to the dolphins, and porpoises. The fossil record suggests that sperm whales were more common in the Miocene, where basal lineages (such as "Zygophyseter" and "Naganocetus") existed; other fossil genera assigned to the Physeteridae include "Ferecetotherium", "Helvicetus", "Idiorophus", "Diaphorocetus", "Aulophyseter", "Orycterocetus", "Scaldicetus", and "Placoziphius", while kogiid fossil genera include "Kogiopsis", "Scaphokogia", and "Praekogia". The earliest kogiids are known from the late Miocene, around 7 million years ago.
Physeteroidea | Evolution
The average length and width for the nine specimens was , the smallest length-to-breadth quotient (1.22) for any species in its genus. Omura's whale seen off New Caledonia, the Solomon Islands, West Sumatra, and East Kalimantan showed extenisve scarring from cookiecutter shark bites, indicating they had ventured into deep waters; whereas those off Madagascar did not exhibit them.
Omura's whale | External appearance
Each of the flippers has seven carpals, and a variable number of phalanges in the digits, reportedly ranging from two in the first digit to as many as 10 in the second digit. No true innominate bone exists; it is replaced by a sheet of dense connective tissue. The hyoid bone is unusually large, and presumably has a role in the whale's suction feeding.
Pygmy sperm whale | Anatomy
The only known complete specimens are a 5.3-m (17.4-ft) adult female and her 3.5-m (11.5-ft) male calf. The cow was spindle-shaped, with a triangular dorsal fin with a concave trailing edge set about two-thirds the way back. It was dark gray or black dorsally and white ventrally, with a light thoracic patch created by a diagonal band that extends from behind the eye downwards and back to the dorsal fin. It also has a dark eye patch, rostrum, and flippers.
Spade-toothed whale | Physical description
Lowering the temperature increases the density to have it act as a weight for deep-sea diving, and raising the temperature decreases the density to have it pull the whale to the surface.
Livyatan | Spermaceti organ
When stressed, this fluid is released. The dwarf sperm whale has between 50 and 57 vertebrae–7 neck vertebrae, 12 to 14 thoracic vertebrae, and 29 or 35-to-37 lumbar vertebrae. The variation can either be due to loss of bones during preparation of a specimen, or individual variations. It is not known to be sexually dimorphic.
Dwarf sperm whale | Description
The body of a whale louse is distinctly flat and considerably reduced at the rear. Its legs, especially the back three pairs of legs, have developed into claw-like protuberances with which it clings to its host. Its length ranges from depending on the species.
Whale louse | Appearance
The macroraptorial sperm whales are a paraphyletic fossil group of hyper-predatory stem sperm whales comprising four genera: "Acrophyseter", "Brygmophyseter", "Livyatan", and "Zygophyseter". These macroraptorials all share large, functional, enamel-coated teeth on both the upper and lower jaws, which were used in capturing large prey. In contrast, the modern sperm whale ("Physeter macrocephalus") lacks enamel, teeth in the upper jaw, and the ability to use its teeth to catch prey. However, "Livyatan" belongs to a different lineage than the other macroraptorials, and the development of large size and the spermaceti organ, an organ that is characteristic of sperm whales, are thought to have evolved independently from the other macroraptorials.
Macroraptorial sperm whale | Taxonomy
Currently there is disagreement on what biological purpose or purposes spermaceti serves. It might be used as a means of adjusting the whale's buoyancy, since the density of the spermaceti changes with its phase. Another hypothesis has been that it is used as a cushion to protect the sperm whale's delicate snout while diving. The most likely primary function of the spermaceti organ is to add internal echo or resonator clicks to the sonar echo location clicks emitted by the respiratory organs. This makes it possible for the whale to sense the motion of its prey as well as its position.
Spermaceti | Biological function
The small teeth of "Diaphorocetus" and the bottleneck-like nature of the rostrum suggest that "Diaphorocetus" employed a feeding strategy intermediate between that of raptorial sperm whales like "Acrophyseter" and "Livyatan" and extant sperm whales.
Diaphorocetus | Paleoecology
A typical killer whale distinctively bears a black back, white chest and sides, and a white patch above and behind the eye. Calves are born with a yellowish or orange tint, which fades to white. It has a heavy and robust body with a large dorsal fin up to 1.8 m (5 ft 11 in) tall. Behind the fin, it has a dark grey "saddle patch" across the back. Antarctic killer whales may have pale grey to nearly white backs. Adult killer whales are very distinctive, seldom confused with any other sea creature. When seen from a distance, juveniles can be confused with other cetacean species, such as the false killer whale or Risso's dolphin.
Killer whale | Appearance and morphology
Zygophyseter varolai is an extinct sperm whale that lived during the Tortonian age of the Late Miocene 11.2 to 7.6 million years ago. It is known from a single specimen from the Pietra Leccese Formation in Italy. It was a member of a stem group of fossil macroraptorial sperm whales (often shortened to "raptorial") also including "Brygmophyseter", "Acrophyseter", and "Livyatan". It probably grew to be around in length and shared some characteristics with other raptorials, such as large teeth with tooth enamel that were functional in both the upper and lower jaws which the modern sperm whale ("Physeter macrocephalus") lacks.
Zygophyseter | Introduction
The sex of the 20th-century specimens is not known. By recovering or failing to recover DNA sequences of the Y chromosome, it could, in theory, be resolved. Little material is shared between the Pitt Island specimen and the calvariae, making direct anatomical comparisons problematic.
Spade-toothed whale | Specimens
Its body is round, particularly when well fed, and tapers less smoothly to the head than the tail. The sudden tapering to the base of its neck gives it the appearance of shoulders, unique among cetaceans. The tail-fin grows and becomes increasingly and ornately curved as the animal ages. The flippers are broad and short—making them almost square-shaped.
Beluga whale | Description