Marine Mammal Species Description

Rough-toothed Dolphin

Steno bredanensis

(G. Cuvier in Lesson, 1828)

Photo credit: Wayne Hoggard NOAA/NMFS/SEFSC

Classification

Order: Cetacea
Family: Delphinidae
Alternate Common Names: Black porpoise, steno, slopehead

Status: protected under MMPA

Description:

   Length: 6.6-8.9 ft (2-2.7 m)
   Weight: 198-342 lbs (90-155 kg)

Rough-toothed dolphins got their name because of grooves and ridges on their teeth that make them look rough. They have a long beak that blends smoothly into their melon, unlike other species of dolphins that generally have a crease and distinct difference between the beak and the melon. They have a tall, slightly falcate dorsal fin, a large eye, large flippers set back farther from their head than in other species of delphinid. Rough-toothed dolphins are white underneath from their beak, including their lips, back to past their bellies. Their sides are gray. They have whitish, yellowish, or pinkish spots or blotches on their sides.

Habitat:

Rough-toothed dolphins occur in warm, deep waters. They can be found in areas of the continental shelf and in waters far from shore that ranges in depth from 1640-6562 ft (500-2000 m). They occur most often in schools of 10-20, however schools of 50 individuals have also been recorded. They also school with other species of cetaceans.

Feeding:

Rough-toothed dolphins eat fish and squid. They have been documented cooperatively hunting food. Dives up to 15 minutes long have been recorded for rough-toothed dolphins.

Reproduction:

Female rough-toothed dolphins reach sexual maturity at around 10 years old, and males reach sexual maturity around 14 years old.

Other:

The maximum lifespan of rough-toothed dolphins appears to be about 32-36 years old.

Distribution / Range:

This species occurs in warm temperate and tropical waters worldwide. Off the east coast of the United States, it is most commonly seen in the coastal waters of the southeast.

Similar species:

They are similar to other long-beaked dolphins. They can be identified by the smooth slope of the head between the melon and the beak.

Notes:

References:

Culik, B. 2010. Odontocetes. The toothed whales: "Steno bredanensis ". UNEP/CMS Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm. Accessed January 2012.

Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. 2008. Steno bredanensis. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. www.iucnredlist.org. Downloaded on 09 January 2012.

Jefferson, T.A. 2009. Rough-Toothed Dolphin - Steno bredanensis. In: Encyclopedia of Marine Mammals 2nd Ed. Perrin W.F., B. Würsig, and J.G.M. Thewissen, eds. Academic Press, New York, pp. 990-992.

Newcomer, M.W. 1999. Rough-toothed dolphin, Steno bredanensis. In The Smithsonian Book of North American Mammals. Wilson, D.E. and S. Ruff, eds., 262-263. Smithsonian Institution in association with the American Society of Mammologists, Washington DC.