Description & Behavior

Rough-toothed dolphins, Steno bredanensis (G. Cuvier in Lesson, 1828), are named for their 20-27 teeth with faint ridges located in both their upper and lower jaws. Adults are up to about 2.8 m long. They are known to reach weights of up to 150 kg. Length at birth is currently unknown.

Their color varies by region within the species, but generally they are dark gray with light spots on their flanks. The ventral (under) side, lower jaw and lips are white and they have a darker marking that extends over their eyes to the upper part of their flanks. Like other marine species, rough-toothed dolphins may show scars resulting from encounters with other marine life such as sharks, squid, and other rough-toothed dolphins.

This species has a distinctive sloped head and indistinct beak. They have large flippers and a central dorsal fin. Rough-toothed dolphins may be confused with bottlenose, spinner, and spotted dolphins, all 3 of which are species that have been observed associating with rough-toothed dolphins.

Steno bredanensis is a gregarious species found in groups of 10-30 on average, as well as schools of up to 160 dolphins containing up to 8 smaller subgroups.

Like other dolphins, rough-toothed dolphins communicate and echolocate using clicks and whistles.

World Range & Habitat

Rough-toothed dolphins, Steno bredanensis, are most commonly found in tropical and subtropical deep waters from the western Pacific to the Mediterranean. They are rarely seen ranging north of 40° latitude or south of 35° latitude.

Rough-toothed dolphin

They have also been seen along the Atlantic coast of the United States, in the Caribbean, Gulf of Mexico, Mediterranean sea, eastern tropical Pacific, and Indian Ocean. Geographic distribution of this species in not well known.

Feeding Behavior (Ecology)

Rough-toothed dolphins, Steno bredanensis, feed on fish and squid and other cephalopods.

Life History

Female rough-toothed dolphins, Steno bredanensis, reach sexual maturity at about 10 years, males at 14 years.

Rough-toothed dolphin

Little is known about the reproductive habits of this species. A rough-toothed dolphin was bred with a bottlenose dolphin in captivity producing a hybrid offspring.

Conservation Status & Comments

Rough-toothed dolphins, Steno bredanensis, are hunted for food in some regions. They are harpooned in Japan and West Africa. Entanglement in fishing gear poses a threat, and rough-toothed dolphins have been reported caught in purse seines in the eastern tropical Pacific. Others have been reported caught in gillnet and driftnet fisheries in Sri Lanka and Brazil.

Pollutants have been detected in blubber analysis of rough-toothed dolphins in Hawaii.

References & Further Research

Jefferson, T.A., S. Leatherwood, and M.A. Webber, FAO species identification guide, Marine mammals of the world, Rome, FAO. 1993. 320 p. 587 figs.
Whale and Dolphin Conservation Society (WDCS)

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View related species: Animalia Chordata Mammalia Cetartiodactyla Delphinidae Steno bredanensis