Pygmy sperm whale
| Pygmy sperm whale | |
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| Illustration from the 19th century | |
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| Size compared to an average human | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Family: | Kogiidae |
| Genus: | Kogia |
| Species: | K. breviceps |
| Binomial name | |
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Kogia breviceps Blainville, 1838 |
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| Pygmy sperm whale range | |
| Synonyms | |
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Euphysetes breviceps |
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Euphysetes breviceps
The pygmy sperm whale (Kogia breviceps) 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.
Debate exists as to the correct classification of the pygmy and dwarf sperm whales (see sperm whale family for details). The two were widely considered to be the same species, until 1966, when a scientist at the Smithsonian Institution definitively identified them as separate species. The pygmy sperm whale was first named by Henri Marie Ducrotay de Blainville in 1838.
The pygmy sperm whale is not much larger than many dolphins. They are about 1.2 m (3 ft 11 in) at birth, growing to about 3.5 m (11 ft) at maturity. Adults weigh about 400 kg (880 lb). 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. 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.
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.
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. 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.
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Wikipedia