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Northern right whale dolphin
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Northern right whale dolphin
The northern right whale dolphin (Lissodelphis borealis) is a small, slender species of cetacean found in the cold and temperate waters of the North Pacific Ocean. Lacking a dorsal fin, and appearing superficially porpoise-like, it is one of the two species of right whale dolphin.
The northern right whale dolphin has a streamlined body with a sloping forehead, and a slimmer build than other delphinids. It lacks any fin or ridge on the smoothly curving back. Its body is nearly all-black with a white ventral marking, extending forward as a narrow band from the caudal peduncle to the throat region, where the patch widens. In females, this white band is wider in the genital area than in males. In southern right whale dolphins (Lissodelphis peronii), the white patch extends higher on the posterior flanks and head. Calves, which are born initially creamy-dark grey or brown, attain adult colouring by the age of one year.
The beak of northern right whale dolphins is short and well-defined, characterised by a straight mouthline. The flippers are small, curved, narrow and pointed. The tail flukes are triangular and, like the flippers, rather pointed.
Adults are 2–3 meters (6.6–9.8 ft) long and weigh between 60–100 kg (130–220 lb). Females (2.3–2.6 m) are generally smaller than males (around 3 m). Otherwise the sexes appear similar.
Northern right whale dolphins have between 80 and 95 thin, sharp teeth, which are not externally visible, used for catching small fish and squid.
Northern right whale dolphins have been observed traveling in pods of up to 110 (eastern North Pacific) to 200 (western North Pacific) individuals; however, larger pods, containing as many as 3,000 dolphins, have been reported. A gregarious species, they often associate with Pacific white-sided dolphins (Lagenorhynchus obliquidens), but have also been observed with Baird's beaked whales (Berardius bairdii), Dall's porpoises (Phocoenoides dalli), humpback whales (Megaptera novaeangliae), pilot whales (Globicephala macrorhynchus), Risso's dolphins (Grampus griseus) and sperm whales (Physeter macrocephalus), among others.
Data on growth and reproduction of right whale dolphins is limited. Examination of northern right whale dolphins caught in driftnets allowed for an estimation of the average age of sexual maturity; in males, it was estimated to be 9.9 and 10.1 years and, in females, 9.7 and 10.4 years. Average length at sexual maturity was estimated at 215.1 cm and 214.7 cm in males and 201.1 cm and 199.8 cm in females. The mass of a mature testis was between 117.4 g to 1300 g. Gestation period was 12.1 to 12.3 months and calving seemed to peak during summer (July and August). The minimum calving interval was two years. An asymptotic length of 265 cm and 210 cm was reached in males and females, respectively.
Northern right whale dolphins have an encephalization quotient (a measure of intelligence) of 5.55, which is the highest for any living species except humans.
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Northern right whale dolphin
The northern right whale dolphin (Lissodelphis borealis) is a small, slender species of cetacean found in the cold and temperate waters of the North Pacific Ocean. Lacking a dorsal fin, and appearing superficially porpoise-like, it is one of the two species of right whale dolphin.
The northern right whale dolphin has a streamlined body with a sloping forehead, and a slimmer build than other delphinids. It lacks any fin or ridge on the smoothly curving back. Its body is nearly all-black with a white ventral marking, extending forward as a narrow band from the caudal peduncle to the throat region, where the patch widens. In females, this white band is wider in the genital area than in males. In southern right whale dolphins (Lissodelphis peronii), the white patch extends higher on the posterior flanks and head. Calves, which are born initially creamy-dark grey or brown, attain adult colouring by the age of one year.
The beak of northern right whale dolphins is short and well-defined, characterised by a straight mouthline. The flippers are small, curved, narrow and pointed. The tail flukes are triangular and, like the flippers, rather pointed.
Adults are 2–3 meters (6.6–9.8 ft) long and weigh between 60–100 kg (130–220 lb). Females (2.3–2.6 m) are generally smaller than males (around 3 m). Otherwise the sexes appear similar.
Northern right whale dolphins have between 80 and 95 thin, sharp teeth, which are not externally visible, used for catching small fish and squid.
Northern right whale dolphins have been observed traveling in pods of up to 110 (eastern North Pacific) to 200 (western North Pacific) individuals; however, larger pods, containing as many as 3,000 dolphins, have been reported. A gregarious species, they often associate with Pacific white-sided dolphins (Lagenorhynchus obliquidens), but have also been observed with Baird's beaked whales (Berardius bairdii), Dall's porpoises (Phocoenoides dalli), humpback whales (Megaptera novaeangliae), pilot whales (Globicephala macrorhynchus), Risso's dolphins (Grampus griseus) and sperm whales (Physeter macrocephalus), among others.
Data on growth and reproduction of right whale dolphins is limited. Examination of northern right whale dolphins caught in driftnets allowed for an estimation of the average age of sexual maturity; in males, it was estimated to be 9.9 and 10.1 years and, in females, 9.7 and 10.4 years. Average length at sexual maturity was estimated at 215.1 cm and 214.7 cm in males and 201.1 cm and 199.8 cm in females. The mass of a mature testis was between 117.4 g to 1300 g. Gestation period was 12.1 to 12.3 months and calving seemed to peak during summer (July and August). The minimum calving interval was two years. An asymptotic length of 265 cm and 210 cm was reached in males and females, respectively.
Northern right whale dolphins have an encephalization quotient (a measure of intelligence) of 5.55, which is the highest for any living species except humans.
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