Description
Pilot whales are mostly dark grey, brown or black, but have some light areas such as a grey saddle pitch behind the dorsal fin. Other light areas are an anchor-shaped patch under the chin, a faint blaze marking behind the eye, a large marking on the belly and a genital patch. The dorsal fin is set forward on the back and sweeps backwards. A pilot whale is more robust than most dolphins and has a distinctive large, bulbous melon. Pilot whales have long, sickle-shaped flippers and tail stocks that are flattened from side to side. Male long-finned pilot whales develop have more circular melons than females, although this does not seems to be the case for short-finned pilot whales off the Pacific coast of Japan.
Long and short-finned pilot whales are so similar that it is difficult to tell the two species apart. They were traditionally differentiated by the length of the pectoral flippers relative to total body length and the number of teeth. The long-finned pilot whale was thought of as having 9-12 teeth in each row and flippers 1/5 of total body length, compared to the short finned pilot whale with its 7-9 teeth in each row and flippers 1/6 of total body length. Studies of whales in the Atlantic showed much overlap in these characteristics between the species, making them clines instead of distinctive features. Thus, biologists have since used skull differences to distinguish the two species. The skull of the short-finned pilot whale has a shorter and broader rostum with a premaxilla that covers more of the maxilla. By contrast, the long-finned pilot whale's skull has a more enlongated rostum and a more exposed maxille.
The size and weight depend on the species as long-finned pilot whales are generally larger than short-finned pilot whales. Their life span is about 45 years in males and 60 years in females for both species. Both species exhibit sexual dimorphism. Adult long-finned pilot whales reach a body length of approximately 6.5 m, with males being 1 m longer than females. Their body mass reaches up to 1,300 kg in females and up to 2,300 kg in males. For short-finned pilot whales, adult females reach a body length of approximately 5.5 m, while males reach 7.2 m and may weigh up to 3,200 kg.
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