Rough-toothed dolphin
Steno bredanensis
Threat Index

Max Length:
Male: 2.80 m
Female: 2.65 m
Calf: 1.00 m

Max Weight:
Male: 160 kg

Est. Population: 150,000

Diet: fish (may be specialist mahi-mahi feeders), squid

IUCN Listing: LC
CMS Appendix: Not Listed
CITES Appendix: II
Synonym:
Slopehead, Rough-toothed dolphin

Related Projects:
None

Classification:
This primitive-looking dolphin gets the name rough-toothed from the unusual construction of its teeth. The teeth have fine vertical wrinkles, impossible to see on live animals but which can be used to identify the animal after death. The rough-toothed dolphin is still however, relatively easy to identify at sea although there may be initial confusion with bottlenose, spotted or spinner dolphins, with whom they are known to associate in the wild. Closer examination of the odd rostrum and body scars will ensure the correct identification.

Appearance:
The rough-toothed dolphin is unusual among oceanic dolphins with a prominent beak because it does not have a crease separating its beak from its melon. The long beak is not well defined and slopes smoothly from the blowhole, giving the head a conical shape. It has relatively large eyes and these, along with the narrow head and long, dark, powerful body give it a somewhat reptilian appearance. The dorsal fin is falcate to triangular, and it has proportionately large flippers and broad flukes, while males have a pronounced keel. The tip of the beak is pale pink and makes for an easy identifying characteristic, as well as the lips which can be white It is generally dark or bluish grey in colour with a darker narrow dorsal cape, the belly and chin are white or pinkish, and it often has large irregular white or pink genital patches. The rough-toothed dolphin often has quite a few white scars, scratches, and other marks on its body; many of these result from close encounters with cookie-cutter sharks.

Behaviour:
Rough-toothed dolphins are not extremely active animals, though they can be fast, powerful swimmers. They often swim with several individuals together shoulder-to-shoulder. They are also seen swimming with the tip of the beak and chin out of the water, facilitating species identification. Rough-toothed dolphins do not generally porpoise but may perform low breaches, and will occasionally bow and wake-ride, though they do this less often than some other species. They tend to travel in small groups of between 10-20 animals, though they can occasionally be seen in larger groups.

Distribution:
The rough-toothed dolphin is a tropical to warm water species present in all three major oceans and usually encountered in deeper offshore waters. Despite its widespread distribution it has not been well studied. In the Atlantic, it is best known from West Africa to the Iberian Peninsula. Threats to the rough-toothed dolphin include small numbers of intentional takes as well as accidental death resulting from bycatch. With an estimated global population of approx. 150,000, the IUCN Red List lists the species as of Least Concern.