Sperm Whale - Description - Size

Size

The sperm whale is the largest toothed whale, with adult males measuring up to 20.5 metres (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 Nantucket Whaling Museum has a 5.5 metres (18 ft)-long jawbone. The museum claims that this individual was 80 feet (24 m) long; the whale that sank the Essex (one of the incidents behind Moby-Dick) was claimed to be 85 feet (26 m). A similar size is reported from a jawbone from the British Museum of Natural History. A 67-foot specimen also is reported from a Soviet whaling fleet near the Kurile Islands in summer of 1965. However, there is disagreement on the claims of adult males approaching or exceeding 80 feet (24 m) in length.

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 metres (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.

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.