Taxonomy/Description

Risso's dolphins belong to the Mammalian Order Cetacea, in the suborder Odontoceti.  All toothed whales belong to the suborder Odontoceti, which is Latin for "toothed whales".  This dolphin belongs to the oceanic dolphin family, Delphinidae.  Other members of this family include the killer whale, long-beaked common dolphin, and pilot whale.  Risso's dolphin's scientific name is Grampus griseus.  The generic name, Grampus, is probably derived from the Spanish grand pez, meaning "great fish". The specific name, griseus, is derived from the Latin gris, meaning "gray".  This refers to the gray coloration of the animal.  This animal is named for Antoine Risso (1777-1845), a French naturalist.

Risso's dolphins reach 9-12ft in length and 900-1000lbs in weight.  Adults are grayish in color, with darker dorsal and pectoral fins. The underside and melon are lighter.  Large white streaks mark the dolphin's entire body.  These are healed scars from aggressive engagements with other Risso's dolphins.  Risso's dolphin has a bulbous head with no prominent beak.

Habitat/Diet

 Native to all temperate and tropical ocean waters, Risso's dolphin prefers the deep, open ocean.  Their diet consists primarily of squid and fish.

Behavior/Reproduction

Groups of 12 or fewer Risso's dolphins are commonly observed.  Migration to cooler waters may occur during the summer months.  Calving appears to take place during the warmer months.  Newborn calves are 4-5ft in length and are solid gray in color.  Calves are solid gray because they have not been subjected to the same scarring as adults.

Conservation

Risso's dolphin is thought to be quite numerous worldwide, with the exception of a few regions.  Although not directly hunted by American fisherman, Risso's dolphin is commercially exploited by Japanese and Filipino fisheries.  Gillnets are a common threat to Risso's dolphin throughout Southeast Asia.