Taxonomy & Nomenclature
Physical Description / Field Identification
Heavisides’s dolphin is one of the most poorly-known of all cetaceans. The shape of the body is similar to that in other Cephalorhynchus dolphins stocky, with a short blunt snout, and blunt-tipped flippers. The dorsal fin is more triangular than the rounded fins of the other genus members, but it is taller than in most porpoises.
The body is predominantly gray, with a dark cape, which starts at the blowhole, remains extremely narrow in the thoracic region and then widens to dip low on the side below the dorsal fin. The area around the eye and much of the face is often darker gray. There is a white ventral patch that begins just behind the flippers, and splits into three arms behind the umbilicus. The middle arm encloses the urogenital area and the side arms extend only to below the mid-line. There is also a white diamond-shaped patch between the anterior insertions of the flippers, and separate white spots in the axillae. Several predominantly white individuals have been seen.
Heaviside’s dolphins have 22-28 small, sharp teeth in each tooth row.
Adults of this species are up to about 1.7 m in length. Newborn size is unknown, but is likely to be somewhat less than 1 m.
Can be Confused With
The only other small cetaceans within this species’ range are larger dolphins, whose falcate dorsal fins should be easy to distinguish.
Distribution
This species of dolphin is restricted to southwest Africa, with records from about 17°S to the southern tip of Africa. It is commonly seen along the west coast of South Africa in the Capetown region. As are other species in the genus, it is a coastal animal.
Ecology and Behavior
Very little is known of the biology of this species. They are seen mostly in small groups of less than 10, with pairs and trios being most common. Heaviside’s dolphins are generally active and sometime boisterous; they are known to ride bow waves.
Essentially, nothing is known of their reproductive biology.
Feeding and Prey
The main diet of Heaviside’s dolphin is demersal fish, such as hake. Some other pelagic schooling fishes and cephalopods are also taken.
Threats and Status
In general, Heaviside’s dolphin appears to be facing fewer threats than the other members of its genus. Some animals are known to be taken incidentally in fisheries, such as purse seines and gillnets - the latter are of particular concern. Some animals are apparently taken for human consumption as well. The major worry is the limited range of the population. Currently, they are listed as “Data Deficient” (IUCN) and “Not Listed” (ESA).
Links
References
Dawson, S.M. 2002. Cephalorhynchus dolphins: Cephalorhynchus heavisidii, C. eutropia, C. hectori and C. commersonii. pp. 200-203 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.
Best, P.B. and R.B. Abernethy. 1994. Heaviside’s dolphin Cephalorhynchus heavisidii (Gray, 1828). pp. 289-310 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Volume 5: The first book of dolphins. Academic Press.
Rice, F.H. and G.S. Saayman. 1984. Movements and behaviour of Heaviside’s dolphin (Cephalorhynchus heavisidii) off the western coast of southern Africa. Investigations on Cetacea 16:49-63.
Rice, F.H. and G.S. Saayman. 1989. Further information on movements and behaviour of Heaviside’s dolphin (Cephalorhynchus heavisidii) off the western coasts of southern Africa. Informal Paper 1:1-9
