Physeteroidea is a

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

that includes three

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

species of

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

s: the

sperm whale 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 famil ...

, in the genus ''Physeter'', and the

pygmy sperm whale 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 spec ...

and

dwarf sperm whale 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 n ...

, in the genus ''Kogia''. In the past, these genera have sometimes been united in a single family, the Physeteridae, with the two ''Kogia'' species in the subfamily Kogiinae; however, recent practice is to allocate the genus ''Kogia'' to its own family, the Kogiidae, leaving the Physeteridae as a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

(single extant species) family, although additional fossil representatives of both families are known.

Characteristics

The sperm whale (''Physeter macrocephalus'') is the largest species of

toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species ...

, 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 bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Ea ...

s of these whales are distinctly asymmetrical, with the

blowhole Blowhole may refer to: * Blowhole (anatomy), the hole at the top of a whale's or other cetacean's head *Blowhole (geology), a hole at the inland end of a sea cave **Kiama Blowhole in Kiama, Australia **The Blow Hole, a marine passage between Minst ...

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. All species have a large number of similar, and relatively simple, teeth. In the kogiids, and sometimes also in the sperm whale, the teeth in the upper jaw do not erupt, and are sometimes altogether absent. The eyes of physeteroids are unable to swivel in their sockets, and possess only a vestigial anterior chamber. Echolocation likely is a far more important sense to these animals than

vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain und ...

. Another common characteristic is the

spermaceti Spermaceti 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 s ...

, a semiliquid waxy white substance filling the 'case' or spermaceti organ in the whale's head, which plays a primary role in the production and directional manipulation of focused clicking sounds used for echolocation in the extant great sperm whale (''Physeter macrocephalus''). All three species dive to great depths to find food, although the sperm whale is believed to dive much deeper than either of the kogiids. Members of both families eat squid, fish, and even sharks.

Gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during preg ...

lasts from 9 to 15 months, depending on species. The single

calf Calf most often refers to: * Calf (animal), the young of domestic cattle. * Calf (leg), in humans (and other primates), the back portion of the lower leg Calf or calves may also refer to: Biology and animal byproducts *Veal, meat from calves ...

remains with the mother for at least two years, before being

weaned Weaning is the process of gradually introducing an infant human or another mammal to what will be its adult diet while withdrawing the supply of its mother's milk. The process takes place only in mammals, as only mammals produce milk. The infa ...

. Physeteroids do not reach full sexual maturity for several years. All species congregate in 'pods' or herds, consisting of mostly females, calves, and adolescent males, although these pod sizes are typically smaller in the kogiids.

Evolution

The earliest sperm whale fossils are known from the late

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but ...

– about 25 million years ago, with an ancestry tracing back from the latest

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

before diverging from the remainder of the odontocetid line, leading to the

dolphin A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (t ...

s, and

porpoise Porpoises are a group of fully aquatic marine mammals, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). Although similar in appearance to dolphins, they are more closely related to narwhals ...

s. The

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

record suggests that sperm whales were more common in the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

, during which basal lineages (such as ''

Zygophyseter ''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 gr ...

'' and ''

Brygmophyseter ''Brygmophyseter'', known as the biting sperm whale, is an extinct genus of toothed whale in the sperm whale family with one species, ''B. shigensis''. When it was first described in 1994, the species was placed in the genus '' Scaldicetus'' b ...

'') existed; other fossil genera assigned to the Physeteridae include '' Ferecetotherium'', '' Helvicetus'', '' Idiorophus'', ''

Diaphorocetus ''Diaphorocetus'' is an extinct genus of odontocete cetacean belonging to Physeteroidea. Its remains were found in the Monte León Formation of Argentina, dating to the Early Miocene.Aulophyseter'', ''

Orycterocetus ''Orycteocetus'' is an extinct genus of sperm whale from the Miocene of the northern Atlantic Ocean. Classification ''Orycterocetus'' is a member of Physeteroidea closely related to crown-group sperm whales. The type species, ''O. quadratiden ...

'', ''

Scaldicetus ''Scaldicetus'' is an extinct genus of highly predatory macroraptorial sperm whale. Although widely used for a number of extinct physeterids with primitive dental morphology consisting of enameled teeth, ''Scaldicetus'' as generally recognized ...

'', 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. The close relationship between extant Physeteridae and Kogiidae is confirmed in recent molecular studies using mitochondrial cytochrome ''b'',; on the basis of these analyses, their nearest relatives appear to be the

Ziphiidae Beaked whales (systematic name Ziphiidae) are a Family (biology), family of cetaceans noted as being one of the least known groups of mammals because of their deep-sea habitat and apparent low abundance. Only three or four of the 24 species are ...

on one hand, and the

Mysticeti Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their ...

and Platanistidae on the other. The last cited paper also favours the grouping of Physeteridae and Kogiidae in a single superfamily, Physeteroidea, as has sometimes previously been suggested. Bianucci & Landini, 2006 suggest that ''Diaphorocetus'', ''Zygophyseter'', ''Naganocetus'', and ''Aulophyseter'' antedate the inferred split of the Kogiidae and Physeteridae, thus would restrict the family Physeteridae to those genera that postdate this split (a

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived ch ...

view).

Classification

They are members of the

Odontoceti The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species o ...

, the

suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

containing all the toothed whales and dolphins. Suggestions that the sperm whales might be a sister group to the baleen whales were refuted by molecular and morphological data, confirming the monophyly of Odontoceti including sperm whales. One extant species of the genus '' Physeter'' is placed in the family Physeteridae. Two species of the related extant genus ''Kogia'', the

''K. breviceps'' and the

''K. simus'', are sometimes also placed in this family, or else are placed in their own family, the

Kogiidae Kogiidae is a family comprising at least two extant species of Cetacea, the pygmy (''Kogia breviceps)'' and dwarf (''K. sima)'' sperm whales. As their common names suggest, they somewhat resemble sperm whales, with squared heads and small lower ...

. A summary of the classification of extant and extinct (†) taxa is: Livyatan melvillei skull

* Physeteroidea, sperm whales **

Stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushr ...

physeteroids *** ''

Acrophyseter ''Acrophyseter'' is a genus of extinct sperm whales that lived in the Late Miocene off the coast of Peru comprising two species: ''A. deinodon'' and ''A. robustus''. It is part of a group of macroraptorial sperm whales which all shared several ...

'' *** '' Albicetus'' *** '' Aulophyseter'' *** ''

'' (= ''Naganocetus'') *** ''

Livyatan ''Livyatan'' is an extinct genus of macroraptorial sperm whale containing one known 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 ...

'' *** '' Miophyseter'' *** ''

'' *** '' Rhaphicetus'' *** ''

'' ** Physeteridae, sperm whales *** '' Cozzuoliphyseter'' *** '' Ferecetotherium'' *** '' Helvicetus'' *** ''

Idiophyseter ''Idiophyseter'' is a genus of macroraptorial sperm whale from the Miocene. Its fossils have been found in Templeton California. ''Idiophyseter'' was small in size compared to modern genera and its maxilla has single-rooted alveoli. It lacked ve ...

'' *** '' Idiorophus'' *** ''

'' *** '' Physeter'', sperm whales **** ''

Physeter macrocephalus ''Physeter'' is a genus of toothed whales. There is only one living species in this genus: the sperm whale (''Physeter macrocephalus''). Some extremely poorly known fossil species have also been assigned to the same genus including ''Physeter ant ...

'', sperm whale *** '' Physeterula'' *** '' Placoziphius'' *** '' Preaulophyseter'' *** ''

'' **

*** ''

Aprixokogia ''Aprixokogia'' is an extinct genus of cetacean in the family Kogiidae that lived during the Pliocene in what is now North Carolina. It shared its habitat with ancestors of the modern pilot whale and pygmy right whale, as well as sea turtles an ...

'' *** ''

Kogia ''Kogia'' is a genus of toothed whales within the superfamily Physeteroidea comprising two extant and two extinct species from the Neogene * Pygmy sperm whale, ''Kogia breviceps'' * Dwarf sperm whale, ''Kogia sima'' *†''Kogia pusilla ''K ...

'', small sperm whales **** ''

Kogia breviceps 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 spec ...

'', pygmy sperm whale **** ''

Kogia sima 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 ...

'', dwarf sperm whale **** ''

Kogia pusilla ''Kogia pusilla'' is an extinct species of sperm whale from the Middle Pliocene of Italy related to the modern day dwarf sperm whale (''K. sima'') and pygmy sperm whale (''K. breviceps''). It is known from a single skull discovered in 1877, a ...

'' *** '' Kogiopsis'' *** '' Praekogia'' *** '' Scaphokogia'' *** '' Thalassocetus''

''Nomina dubia''

* '' Eucetus'' * '' Graphiodon'' * '' Homocetus'' * '' Hoplocetus'' * '' Orcopsis'' * '' Palaeodelphis'' * '' Paleophoca'' * '' Physetodon'' * '' Physodon'' * '' Physotherium'' * '' Priscophyseter'' * '' Prophyseter'' * '' Scaptodon'' * '' Ziphoides''

References

{{Authority control * Extant Chattian first appearances Taxa named by John Edward Gray