by: Nicole Le Boeuf
This species was named for the rough texture of its teeth which have vertical wrinkles or grooves on them. The word steno come from the Greek word "stenos" meaning narrow which probably refers to the sloping of the foreward to a narrow point. Bredanensis is taken from, Van Breda, the artist's name who painted the type specimen.
Unlike most dolphins, rough-toothed dolphins have no visible demarcation between the melon and the rostrum, but rather the forehead slopes gently on all sides to the end of the snout. This creates the appearance of a cone-shaped head. The body is dark gray to black with the underside as well as the regions of the lips and jaws being white. They have a narrow dorsal cape along their bodies, and they are often covered with numerous white scars and scratches.
The body shape is usually robust much like the bottlenose dolphin, and it may reach up to 2.8 m in length. They generally weigh about 150 kg at adulthood, but birth size is unknown.
This is a fairly cosmopolitan species inhabiting all tropical and subtropical seas staying primarily in deeper, off-shore waters. They are found off of all Africa's coastlines except that of the Meditteranean Sea and are widespread throughout the Indian Ocean.
The flippers and the flukes of this species are unusally large for its body size with the flippers reaching up to one-seventh and the width of the flukes reaching one-fourth of the animal's total body length. Little is known about rough-toothed dolphins, but they are notable for their "surfing" behavior during which they swim at a high rate of speed their and chins above the water as they skim across the surface.
Some rough-toothed dolphins have been taken from the wild to be held in captivity. Some are also taken in fisheries in Sri Lanka. They are also involved in drive fisheries in Japan as well as in incidental catches in Eastern Tropical Pacific fisheries.
Insufficiently known.
Jefferson, T.A. Leatherwood, S. and M.A. Webber. 1994. FAO Species Identification Guide, Marine Mammals of the World. FAO of the United Nations, Rome.
Jefferson, T.A., Curry, B.E., Leatherwood, S. and J.A. Powell. 1997. Dolphins and porpoises of West Africa: A review of records (Cetacea: Delphinidae, Phocoenidae). Mammalia, v61 i1 pp 87-108 (22).
Leatherwood, S. and R.R. Reeves. 1987. The Sierra Club Handbook of Whales and Dolphins. Sierra Club Books, San Fransisco.
Steiner L. Rough-toothed dolphin, Steno bredanensis: A new species record for the Azores, with some notes on behaviour. Arquipelago Boletim Da Universidade Dos Acores Ciencias Biologicas e Marinhas 0(13A). 1995. 125-127.
Miyazaki N. Perrin W F. Rough-toothed dolphin Steno bredanensis (Lesson, 1828). Ridgway, S. H. and R. Harrison (Ed.). Handbook of Marine Mammals, Vol. 5. The first book of dolphins. xx+416p. Academic Press, Ltd.: London, England, UK; San Diego, California, USA. ISBN 0-12-588505-9. 1994. 1-21.
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