Sperm whale family
Encyclopedia
Physeteroidea is a superfamily including just three living species of whale
; the Sperm Whale
, in the genus Physeter, and the Pygmy Sperm Whale
and Dwarf Sperm Whale
, in the genus Kogia. In the past these genera have sometimes been united in a single family, Physeteridae, with the two Kogia species in a subfamily (Kogiinae), however recent practice is to allocate the genus Kogia to its own family, Kogiidae, leaving Physeteridae as a monotypic
(single extant species) family, although additional fossil representatives of both families are known (see "Evolution").
The body of sperm whales is robustly proportioned, with paddled-shaped flippers. The lower jaw is always relatively small and thin relative to the upper jaw. The nasal bone
s of sperm 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. 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 sperm whales are unable to swivel in their sockets, and possess only a vestigial anterior chamber
. It is likely that echolocation
is a far more important sense to these animals than vision
.
Another common characteristic is the spermaceti
, a semi-liquid waxy white substance filling the 'case' or spermaceti organ in the whale's head, which plays the role of a ballast in diving and maintaining buoyancy. This is done by flushing cold water through the nose, hardening the spermaceti, to dive, and pumping warm blood to melt the spermaceti to surface. (See the individual species articles for further details). 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
lasts from nine to fifteen months, depending on species. The single calf remains with the mother for at least two years, before being weaned
. Sperm whales do not reach full sexual maturity for several years. All species congregate together in 'pods' or herds, consisting of mostly females, calfs, and adolescent males, although these pod sizes are typically smaller in the kogiids.
– 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 dolphin
s, and porpoise
s.
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.
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 on one hand, and the Mysticeti 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
pre-date the inferred split of Kogiidae and Physeteridae and thus would restrict the family Physeteridae to those genera that post-date this split (a cladistic view).
Kogia breviceps and the dwarf sperm whale
K. simus, are sometimes also placed in this family, or else are placed in their own family, Kogiidae.
The following is a summary of the classification of extant and extinct (†) taxa:
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
; the Sperm Whale
Sperm Whale
The sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...
, in the genus Physeter, and the Pygmy Sperm Whale
Pygmy Sperm Whale
The Pygmy Sperm Whale is one of three species of toothed whale in the sperm whale family. They are not often sighted at sea, and most of what is known about them comes from the examination of stranded specimens.-Taxonomy:...
and Dwarf Sperm Whale
Dwarf Sperm Whale
The Dwarf Sperm Whale is one of three species in the sperm whale family. They are not often sighted at sea. As such, most information is a result of the study of stranded carcasses.-Taxonomy:...
, in the genus Kogia. In the past these genera have sometimes been united in a single family, Physeteridae, with the two Kogia species in a subfamily (Kogiinae), however recent practice is to allocate the genus Kogia to its own family, Kogiidae, leaving Physeteridae as a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
(single extant species) family, although additional fossil representatives of both families are known (see "Evolution").
Characteristics
The Sperm Whale is the largest species of toothed whale, with adult bulls(males) growing to be about 15–18 m (49.2–59.1 ) long, and weighing about 45–70 t (44.3–68.9 ). The two kogiid species are much smaller, at only around 2.5 to 3.5 m (8.2 to 11.5 ) in length, and weighing 350–500 kg (771.6–1,102.3 ).The body of sperm whales is robustly proportioned, with paddled-shaped flippers. The lower jaw is always relatively small and thin relative to the upper jaw. The nasal bone
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 form, by their junction, "the bridge" of the nose.Each has two surfaces and four borders....
s of sperm whales are distinctly asymmetrical, with the blowhole
Blowhole (biology)
In biology, a blowhole is the hole at the top of a cetacean's head through which the animal breathes air. It is homologous with the nostril of other mammals. As whales reach the water surface to breathe, they will forcefully expel air through the blowhole. Not only is air expelled, but mucus and...
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 sperm whales are unable to swivel in their sockets, and possess only a vestigial anterior chamber
Anterior chamber
The anterior chamber is the fluid-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Aqueous humor is the fluid that fills the anterior chamber. Hyphema and glaucoma are two main pathologies in this area. In hyphema, blood fills the anterior chamber...
. It is likely that echolocation
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
is a far more important sense to these animals than vision
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
.
Another common characteristic is the spermaceti
Spermaceti
Spermaceti is a wax present in the head cavities of the sperm whale . Originally mistaken for the whales' sperm , spermaceti is created in the spermaceti organ inside the whale's head and connected to its nasal passage...
, a semi-liquid waxy white substance filling the 'case' or spermaceti organ in the whale's head, which plays the role of a ballast in diving and maintaining buoyancy. This is done by flushing cold water through the nose, hardening the spermaceti, to dive, and pumping warm blood to melt the spermaceti to surface. (See the individual species articles for further details). 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
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
lasts from nine to fifteen months, depending on species. The single calf remains with the mother for at least two years, before being weaned
Weaning
Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother's milk.The process takes place only in mammals, as only mammals produce milk...
. Sperm whales do not reach full sexual maturity for several years. All species congregate together in 'pods' or herds, consisting of mostly females, calfs, and adolescent males, although these pod sizes are typically smaller in the kogiids.
Evolution
The earliest sperm whale fossils are known from the late OligoceneOligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
– about 25 million years ago, with an ancestry tracing back from the latest Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
before diverging from the remainder of the Odontocetid line, leading to the dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
s, and porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
s.
The fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
record suggests that sperm whales were more common in the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
, where basal lineages (such as Zygophyseter
Zygophyseter
Zygophyseter varolai is an extinct cetacean, similar to the sperm whale. The common name of "killer sperm whale" refers both to its relation to modern day sperm whales, and to its similarity in size to and its "probable similar feeding adaptation to the extant delphinid killer whale ".The...
and Naganocetus) existed; other fossil genera assigned to the Physeteridae include Ferecetotherium, Helvicetus, Idiorophus, Diaphorocetus, Aulophyseter
Aulophyseter
Aulophyseter is an extinct genus of sperm whale from the Miocene formations of the West and East coasts of North America as well as the Patagonian region of South America...
, Orycterocetus
Orycterocetus
Orycterocetus is an extinct genus of sperm whale from the Miocene.-Sources:* Cenozoic Seas: The View From Eastern North America by Edward J. Petuch* Marine Mammals: Evolutionary Biology by Annalisa Berta and James L. Sumich...
, Scaldicetus, and Placoziphius, while kogiid fossil genera include Kogiopsis
Kogiopsis
Kogiopsis is a genus of prehistoric sperm whales from the family Physeteridae. It lived in the mid Miocene. It was up to long. Kogiopsis had very long teeth, long, without root...
, Scaphokogia, and Praekogia. The earliest kogiids are known from the late Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
, 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 on one hand, and the Mysticeti 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
Zygophyseter
Zygophyseter varolai is an extinct cetacean, similar to the sperm whale. The common name of "killer sperm whale" refers both to its relation to modern day sperm whales, and to its similarity in size to and its "probable similar feeding adaptation to the extant delphinid killer whale ".The...
, Naganocetus and Aulophyseter
Aulophyseter
Aulophyseter is an extinct genus of sperm whale from the Miocene formations of the West and East coasts of North America as well as the Patagonian region of South America...
pre-date the inferred split of Kogiidae and Physeteridae and thus would restrict the family Physeteridae to those genera that post-date this split (a cladistic view).
Classification
Members of the suborder Odontoceti, the suborder containing all the toothed whales and dolphins. One extant species of the genus Physeter, which is placed in the family Physeteridae. Two species of the related extant genus Kogia, the pygmy sperm whalePygmy Sperm Whale
The Pygmy Sperm Whale is one of three species of toothed whale in the sperm whale family. They are not often sighted at sea, and most of what is known about them comes from the examination of stranded specimens.-Taxonomy:...
Kogia breviceps and the dwarf sperm whale
Dwarf Sperm Whale
The Dwarf Sperm Whale is one of three species in the sperm whale family. They are not often sighted at sea. As such, most information is a result of the study of stranded carcasses.-Taxonomy:...
K. simus, are sometimes also placed in this family, or else are placed in their own family, Kogiidae.
The following is a summary of the classification of extant and extinct (†) taxa:
- Physeteroidea, sperm whales
- stem physeteroids
- Diaphorocetus †
- AcrophyseterAcrophyseterAcrophyseter is a genus of stem-sperm whales that lived around 6 million years ago.-Description:Acrophyseter is derived from the Greek akros, meaning acute, which describes the short, pointed upturned snout, and Physeter, the scientific name for sperm whales. But unlike today's sperm whales, A...
† - ZygophyseterZygophyseterZygophyseter varolai is an extinct cetacean, similar to the sperm whale. The common name of "killer sperm whale" refers both to its relation to modern day sperm whales, and to its similarity in size to and its "probable similar feeding adaptation to the extant delphinid killer whale ".The...
† - BrygmophyseterBrygmophyseterBrygmophyseter is an extinct genus of toothed whale in the sperm whale family with one species Brygmophyseter shigensis. When first described, this species was placed in an extinct form genus Scaldicetus of toothed whale, as Scaldicetus shigensis)...
(= Naganocetus) † - AulophyseterAulophyseterAulophyseter is an extinct genus of sperm whale from the Miocene formations of the West and East coasts of North America as well as the Patagonian region of South America...
† - LivyatanLivyatan melvilleiLivyatan melvillei is an extinct species of physeteroid whale, which lived during the Miocene epoch, approximately 12-13 million years ago.- Discovery :...
†
- Physeteridae, sperm whales
- Physeter, sperm whales
- Physeter macrocephalusSperm WhaleThe sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...
, sperm whale
- Physeter macrocephalus
- OrycterocetusOrycterocetusOrycterocetus is an extinct genus of sperm whale from the Miocene.-Sources:* Cenozoic Seas: The View From Eastern North America by Edward J. Petuch* Marine Mammals: Evolutionary Biology by Annalisa Berta and James L. Sumich...
† - Ferecetotherium †
- Helvicetus †
- Idiorophus †
- Placoziphius †
- Idiophyseter †
- Physeterula †
- Physeter, sperm whales
- Kogiidae
- Kogia, small sperm whales
- Kogia breviceps, pygmy sperm whale
- Kogia sima, dwarf sperm whale
- Aprixokogia †
- KogiopsisKogiopsisKogiopsis is a genus of prehistoric sperm whales from the family Physeteridae. It lived in the mid Miocene. It was up to long. Kogiopsis had very long teeth, long, without root...
† - Praekogia †
- Scaphokogia †
- Kogia, small sperm whales
- stem physeteroids