What is Heaviside's Dolphin?

Heaviside's Dolphin
Size comparison against an average human Size comparison against an average human
Conservation status
Data deficient (IUCN)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Subclass: Eutheria Order: Cetacea Suborder: Odontoceti Genus: Cephalorhynchus Species: C. heavisidii
Binomial name
Cephalorhynchus heavisidii Gray, 1828
Heaviside's Dolphin range Heaviside's Dolphin range

Heaviside's Dolphin (Cephalorhynchus heavisidii) is a small dolphin that is found off the coast of Namibia and the west coast of South Africa. It is one of four dolphins in the Cephalorhychus genus - the others being the Chilean Dolphin, Hector's Dolphin and Commerson's Dolphin.

Name

Heaviside's Dolphin is actually named after a Captain Haviside who brought a specimen from Namibia to the United Kingdom early in the 19th Century. However its name was once mis-spelled Heaviside, after a prominent surgeon, Captain Heaviside who collected cetacean and other animal species. The latter name stuck and is the most common in the popular literature. However some authorities, including the Encyclopedia of Marine Mammals and Mammal Species of the World use the originally intended name - Haviside's Dolphin

Population and distribution

Although sightings of the species are not uncommon off the Skeleton Coast of Namibia, Heaviside's Dolphins have not been systematically studied by scientists. They have been recorded off the coast of northern Namibia at 17° S and as far south as the southern tip of South Africa. Sightings are often recorded from major population centres such as Cape Town and towns such as Walvis Bay. Sightings are likely from Lambert's Bay either from the shore or from boat trips run from the Harbour. No estimates of abundance exist.

Physical description

Heaviside's Dolphin is a fairly small dolphin, growing up to about 180 cm in length and weighing up to 75 kg. Their size and the bluntness of their heads leads these dolphins to often be mistaken for porpoises. The head is coloured a dark grey. The front half of the upper side and the flanks are a much lighter grey. The dorsal fin, fluke and back half of the back are again a darker grey colour. The underbelly is white and there are flashes of white on the flanks below the dorsal fin.

Males reach sexual maturity at about 7–9 years. Females reach breeding age at the same time. The gestation period is probably 10 months. Mating occurs in Spring and Summer. It is believed that females calf on average once every three years. The maximum known age of a Heaviside's Dolphin is 20 years. This relatively short life span, coupled with the long calving period, causes a naturally low population growth rate. Therefore the species is particularly sensitive to being hunted.

Heaviside's Dolphins are active and social animals. They typical congregate in groups of about 5–10 in number, and sometimes in larger groups. They are able to swim fast. Part of the play and social activity is to jump vertically clear of the water, turn in the air, and fall back into the sea with virtually no splashing or noise.

References

• Cetacean Specialist Group (1996). Cephalorhynchus heavisidii. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 08 May 2006. Database entry includes justification for why this species is listed as data deficient
• National Audubon Society: Guide to Marine Mammals of the World Reeves, Stewart, Clapham and Powell, (2002)
• Cephalorhynchus dolphins, Encyclopedia of Marine Mammals, p200-202, Stephen M. Dawson (1998) ISBN 0-12-551340-2

External links

• Whale and Dolphin Conservation Society