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Difference between revisions of "Sperm whale"
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[[File:Mother and baby sperm whale.jpg|400px|thumb|A mother sperm whale and her calf off the coast of Mauritius. ]] | [[File:Mother and baby sperm whale.jpg|400px|thumb|A mother sperm whale and her calf off the coast of Mauritius. ]] | ||
The '''sperm whale''' (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of 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''' (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator in the world. It is the only living member of 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 live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade. A mature sperm whale has few natural predators, although calves and weakened adults are sometimes killed by pods of [[orca]]s. | 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 live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade. A mature sperm whale has few natural predators, although calves and weakened adults are sometimes killed by pods of [[orca]]s. | ||
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The sperm whale is the largest toothed whale, with adult males measuring up to 20.5 meters (67 ft) long and weighing up to 57,000 kilograms (56 long tons; 63 short tons). By contrast, the second largest toothed whale (Baird's Beaked Whale) measures 12.8 metres (42 ft) and weighs up to 15 short tons (14,000 kg). | The sperm whale is the largest toothed whale, with adult males measuring up to 20.5 meters (67 ft) long and weighing up to 57,000 kilograms (56 long tons; 63 short tons). By contrast, the second largest toothed whale (Baird's Beaked Whale) measures 12.8 metres (42 ft) and weighs up to 15 short tons (14,000 kg). | ||
Extensive [[whaling]] may have decreased their size, as males were highly sought, primarily after World War II. Today, males do not usually exceed 18.3 meters (60 ft) in length or 51,000 kilograms (50 long tons; 56 short tons) in weight. 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. | Extensive [[whaling]] may have decreased their size, as males were highly sought, primarily after World War II. Today, males do not usually exceed 18.3 meters (60 ft) in length or 51,000 kilograms (50 long tons; 56 short tons) in weight. 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. Old males taken at Solander Islands were recorded to be extremely large and unusually rich in blubbers. | ||
It 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. | It 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. | ||