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See also:     Cetaceans

Rissos dolphin surfacing with eye showing. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #02319, all rights reserved worldwide. Rissos dolphin surfacing with eye showing. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #02314, all rights reserved worldwide. Rissos dolphin, dorsal fin.Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #04970, all rights reserved worldwide.
Note the high, slender, scythe-like dorsal fins and extensive dorsal scarring of these Risso's dolphins. [Image 2319] [Image 2314] A typical group of several dozen Risso's dolphins, seen underwater, Rissos dolphin, dorsal fin.Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. San Diego, Grampus griseus, Image 04970
Risso's dolphins (Grampus griseus) are large oceanic dolphins distributed throughout most of the world's tropical and warm-temperate waters. They typically reach 10 feet (3m) in length as adults, weighing up to 650 lbs (330kg). Research suggests that their preferred prey are squid, although they are known to predate upon fishes as well.
A group of Rissos dolphin surfaces.  Extensive scarring on adult Rissos dolphins allows identification of individuals based on their dorsal fins, provided the identification methodology incorporates scarring acquired in future years. Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07601, all rights reserved worldwide. A group of Rissos dolphin surfaces.  Extensive scarring on adult Rissos dolphins allows identification of individuals based on their dorsal fins, provided the identification methodology incorporates scarring acquired in future years. Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07602, all rights reserved worldwide. Rissos dolphin showing fresh scarring from social interactions with other Rissos dolphins.  Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #04964, all rights reserved worldwide.
Individual Risso's dolphins are easy to distinguish because of the unique scarring patterns borne on their dorsal fins and bodies. [Image 7601] [Image 7602] Extensive scarring makes this adult Risso's dolphin appear almost totally white, Rissos dolphin showing fresh scarring from social interactions with other Rissos dolphins. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. San Diego, Grampus griseus, Image 04964
One distinguishing characteristic of Risso's dolphins are the white scars they acquire (and keep) throughout their lives. It is thought these scars are the result of teeth scrapes from other Risso's dolphins, injuries from parasites and/or squid. In some adults the scarring is so extensive that the animal appears nearly all white (in contrast to the dark gray color seen in juveniles and adults that have no acquired much scarring).
A Rissos dolphin leaps from the ocean in a full breach. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species.  White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07597, all rights reserved worldwide. A Rissos dolphin spyhops, lifting its head above water for a look. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species.  White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07598, all rights reserved worldwide. Rissos dolphin, breaching. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #00983, all rights reserved worldwide.
A full breach, A Rissos dolphin leaps from the ocean in a full breach. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. Offshore near San Diego, Grampus griseus, Image 07597 A spyhop, A Rissos dolphin spyhops, lifting its head above water for a look. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. Offshore near San Diego, Grampus griseus, Image 07598 A full breach. Note this Risso's dolphin's white ventral patch (contrasting against its unscarred dark gray body) is apparent, Rissos dolphin, breaching. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. San Diego, Grampus griseus, Image 00983
The typical lifespan of a Risso's dolphin is estimated to be at least 20 years and perhaps up to 40 years. They often travel in groups of five to 50 animals, and recent evidence suggests that these groups may be stable and composed of related individuals, although this has not been proven. Occasionally many groups will coalesce into a huge herd of many hundreds or thousands of Risso's dolphins. sometimes mixed with other species of dolphin as well.
Rissos dolphins surfacing showing dorsal fins. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #02318, all rights reserved worldwide. Rissos dolphin. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species.  White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07591, all rights reserved worldwide. Rissos dolphin. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species.  White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07593, all rights reserved worldwide.
Rissos dolphins surfacing showing dorsal fins. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. San Diego, Grampus griseus, Image 02318 Rissos dolphin. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. Offshore near San Diego, Grampus griseus, Image 07591 Rissos dolphin. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. Offshore near San Diego, Grampus griseus, Image 07593
Sri Lanka and various Asian societies (including Japan and Taiwan) hunt and consume Risso's dolphins as food.
A young Rissos dolphin calf performs a tail slap. Note the dark color on this juvenile, it has yet to acquire the white scarring that distinguishes adult Rissos dolphins.  Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07599, all rights reserved worldwide. Rissos dolphin. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species.  White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white.  Offshore near San Diego, Grampus griseus, copyright Phillip Colla Natural History Photography, www.oceanlight.com, image #07604, all rights reserved worldwide.
A tail slapping juvenile Risso's dolphin, A young Rissos dolphin calf performs a tail slap. Note the dark color on this juvenile, it has yet to acquire the white scarring that distinguishes adult Rissos dolphins. Offshore near San Diego, Grampus griseus, Image 07599 Rissos dolphin. Note distinguishing and highly variable skin and dorsal fin patterns, characteristic of this species. White scarring, likely caused by other Risso dolphins teeth, accumulates during the dolphins life so that adult Rissos dolphins are almost entirely white. Offshore near San Diego, Grampus griseus, Image 07604

See also:     Atlantic Spotted Dolphin     Pacific White-Sided Dolphin     Hawaiian Spinner Dolphin     Bottlenose Dolphin     Common Dolphin