Clymene dolphin (Stenella clymene)

Also known as: Helmet dolphin
French: Dauphin De Clymène
Spanish: Delfín Clymene
GenusStenella (1)
SizeMale length: 176 – 197 cm (2)
Female length: 171 – 190 cm (2)
Weightup to at least 80 kg (2)

Classified as Data Deficient (DD) on the IUCN Red List (1), and listed on Appendix II of CITES (3).

One of the most recently recognised species of dolphin (2) (4), the Clymene dolphin remains among the least known of the Delphinidae (2). In appearance it is very similar to the spinner dolphin (Stenella longirostris), which is largely why it was not recognised until 1981 as a distinct species. It is a small but stocky dolphin, with a beak of medium length and a dorsal fin that is triangular to nearly triangular. Males are larger and heavier than females, but both sexes have a white belly, light grey flanks and a dark grey cape, and a dark grey line runs down the top of the beak (2) (4). The one distinctive feature that separates the Clymene dolphin in appearance from the spinner dolphin is the black marking, somewhat like a moustache, on top of the beak (2).

The Clymene dolphin occurs in the tropical and warm-temperate waters of the Atlantic Ocean, from West Africa to North America, including the Caribbean and Gulf of Mexico (5).

Clymene dolphins have been generally observed in deep, offshore, tropical and warm-temperate waters, at depths of 44 to 4,500 metres (2) (5).

Clymene dolphins have been seen singly, amongst groups of spinner dolphins, and in large groups of around 100 animals (5). These schools may sometimes be divided by age and sex (2), and sometimes are seen in the company of a group of common dolphins (Delphinus delphis) (4). Clymene dolphins appear to feed in midwater during the night, on fishes and squids, and many bear bite marks and scars from cookie-cutter sharks (Isistius brasiliensis) (4).

These attractive and acrobatic dolphins have been observed riding the bow waves of boats and spinning out of the water like spinner dolphins, although the spins are not as high or as complex as those of performed by the spinner dolphin (4).

While the Clymene dolphin is currently not known to be facing any serious threats, the lack of research on this species means that the problems could simply be undocumented (2). These dolphins are harpooned in the Lesser Antilles and are sometimes caught in fishing gear in other areas (1). Bycatch is likely to occur in many parts of its range, but is thought to be most significant in the eastern tropical Atlantic, off West Africa, where considerable numbers may be taken in tuna purse seines. Clymene dolphins are also captured in this area for food (1) (2).

The Clymene dolphin is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that any international trade in this species should be carefully monitored to ensure its compatibility with the species’ survival (3). The lack of information regarding this species current status has led to the IUCN being unable to assess its risk of extinction, and thus it is classified as Data Deficient (1). Further research into this enchanting marine mammal is clearly needed, particularly into the impact of bycatch and intentional hunting in West Africa, so that conservation measures can be promptly implemented if required.

For further information on dolphins and their conservation see:


Authenticated (17/11/07) by William F. Perrin, Senior Scientist for Marine Mammals, National Marine Fisheries Service, Southwest Fisheries Science Centre.

  1. IUCN Red List (November, 2008)
  2. Jefferson, T.A. (2008) Clymene dolphin. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (Eds) Encyclopedia of Marine Mammals Second Edition. Academic Press, London.
  3. CITES (December, 2007)
  4. Perrin, W.F., Mitchell, E.D., Mead, J.G., Caldwell, D.K. and van Bree, P.J.H. (1981) Stenella clymene, a rediscovered tropical dolphin of the Atlantic. Journal of Mammalogy, 62(3): 583 - 598.
  5. Fertl, D., Jefferson, T.A., Moreno, I.B., Zerbini, A.N. and Mullin, K.D. (2003) Distribution of the Clymene dolphin Stenella clymene. Mammal Review, 33: 253 - 271.