Risso’s dolphin

Grampus griseus

Appearance

Size: 2.6 – 3.8m

Key feature: Body scaringRisso’s dolphins are very distinctive thanks to their unique body scarring. Risso's dolphins are born dark grey, but overtime they obtain scars that stay white. The intensity of this scarring varies, but some older Risso’s dolphins can appear almost white. This scarring is caused by teeth scrapes from other Risso’s dolphins as well as injuries from parasites and squid. Risso’s dolphins have a tall, sickle-shaped fin which is dark and rarely scarred. The dorsal fin can easily be mistaken for that of a killer whale if seen from a distance due to its height and colour. They have a rounded head and has an indistinctive beak.

Behaviour

Risso’s dolphins travel alone or in small groups of up to 20. They feed mainly at night so their day time behaviour usually consists of logging at the surface and travelling slowly. They are highly inquisitive animals, often breaching, spy-hopping and tail slapping. Risso’s dolphins are highly sociable and often seen in association with other cetaceans.

Distribution

They are globally distributed from warm temperate to tropical seas. In Europe they are commonly seen in the western English Channel, Irish Sea and in the Bay of Biscay.

Threats

Alike to other dolphins, Risso’s dolphin's are subject to threats such as entanglement in fishing gear, pollution, collisions with vessels, decreasing availability of prey, anthropogenic sound and habitat degradation. 

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