Heaviside's Dolphin
Encyclopedia
The Haviside's Dolphin (Cephalorhynchus heavisidii), or mistakenly the Heaviside's Dolphin, 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 genus
Cephalorhynchus
— the others being the Chilean Dolphin
, Hector's Dolphin
, and Commerson's Dolphin
.
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 of Haviside's Dolphin.
of Namibia, Haviside'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.
s. 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 Haviside'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.
Haviside's Dolphins are active and social animals. They typically congregate in groups of about 5–10 in number but sometimes in larger groups. They are able to swim fast. Part of their 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.
). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
The Heaviside's dolphin is covered by the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU).
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
that is found off the coast of Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
and the west coast of South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
. It is one of four dolphins in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Cephalorhynchus
Cephalorhynchus
Cephalorhynchus is a genus in the dolphin family Delphinidae. It consists of four species:*Commerson's Dolphin, Cephalorhyncus commersonii*Chilean Dolphin, Cephalorhyncus eutropia*Heaviside's Dolphin, Cephalorhyncus heavisidii...
— the others being the Chilean Dolphin
Chilean Dolphin
The Chilean Dolphin , also known as the Black Dolphin, is one of four dolphins in the Cephalorhynchus genus. The dolphin is only found off the coast of Chile, it is commonly referred to in the country as Tunina....
, Hector's Dolphin
Hector's Dolphin
Hector's dolphin is the best-known of the four dolphins in the genus Cephalorhynchus and is found only in New Zealand. At about 1.4 m in length, it is one of the smallest cetaceans....
, and Commerson's Dolphin
Commerson's Dolphin
Commerson's Dolphin is one of four dolphins in the Cephalorhynchus genus. The species has also the common names Skunk Dolphin, Piebald Dolphin and Panda Dolphin...
.
Name
The Haviside's Dolphin, whose binomial name references heavisidii, is actually named after a Captain Haviside who brought a specimen from Namibia to the United KingdomUnited Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
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 of Haviside's Dolphin.
Population and distribution
Although sightings of the species are not uncommon off the Skeleton CoastSkeleton Coast
The Skeleton Coast is the northern part of the Atlantic Ocean coast of Namibia and south of Angola from the Kunene River south to the Swakop River, although the name is sometimes used to describe the entire Namib Desert coast...
of Namibia, Haviside'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
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
. Sightings are often recorded from major population centres such as Cape Town
Cape Town
Cape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
and towns such as Walvis Bay
Walvis Bay
Walvis Bay , is a city in Namibia and the name of the bay on which it lies...
. 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
The Haviside'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 porpoisePorpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
s. 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
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
, 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 Haviside'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.
Haviside's Dolphins are active and social animals. They typically congregate in groups of about 5–10 in number but sometimes in larger groups. They are able to swim fast. Part of their 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.
Conservation
The Heaviside's dolphin is listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMSBonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
The Heaviside's dolphin is covered by the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU).