T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Dolphin (Risso’s) Grampus griseus

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Delphinidae
Genus: Grampus
Species: G. griseus
Binomial name: Grampus griseus
Common name: Risso’s dolphin, Monk dolphin, Grey dolphin

Risso’s Dolphins inhabit deep oceanic and continental slope waters, generally 400-1,000 m deep. They are found worldwide in tropical and temperate regions of most oceans, usually in deeper waters rather, but close to land. As well as the tropical parts of the Indian, Pacific and Atlantic Oceans, they are also found in the Persian Gulf and the Mediterranean and the Red Sea.
Only a dozen or so have been reported from New Zealand waters. One was a famous Risso’s dolphin named Pelorus Jack who rode the bow waves of ships passing across the outside of Pelorus Sound and Admiralty Bay between 1888 and 1912.

Risso's dolphins have blunt, squarish heads and lack the beak. The dorsal fin is tall and falcate, and their flippers are long, pointed, and recurved. The anterior part of the body is very robust, tapering to a narrow tailstock
The bulbous head has a vertical crease in front. They lack teeth in their upper jaws and have two to seven pairs of teeth in the lower jaw. The dorsal fin is tall and falcate, and their flippers are long, pointed, and recurved. The anterior part of the body is very robust, tapering to a narrow tailstock. They grow up to 4 m in length and can weigh up to 500 kilograms making it the largest species called "dolphin".
This species displays highly variable colouration. This species displays highly variable colouration.
This species displays highly variable colouration. Linear scars mostly from social interaction eventually cover the bulk of the body. Their main diet is squid.
This species is hunted for food in some places and it is as fertilizer in Japan. (The IUCN Red List).



A Risso’s dolphin at the surface, showing the high pointed fin and the usually extensive scarring the body.


A diagram showing the size difference of Risso’s dolphin and a human.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/http://www.terrain.net.nz/uploads/images/Te%20Henui/Faunatwo/1-1-rosso's%20dolphen_Reconstitution.jpg