FaunaHub

Risso's Dolphin (Grampus griseus)

Marine mammalDolphin familyHighly intelligentDeep diver

Risso's dolphin (Grampus griseus) surfacing off Catalina, California.

Risso's dolphin (Grampus griseus), California.

Image: Kiloueka, CC0, via Wikimedia Commons.

Overview

Risso's dolphin (Grampus griseus) is a large, robust dolphin easily recognised by its blunt, beakless head and pale grey body covered in a network of scratches and scars. Older animals can appear almost white from the accumulated markings, which come from interactions with other Risso's dolphins and from the squid they hunt.

A deep-water specialist, Risso's dolphin is found in temperate and tropical seas worldwide and, like other dolphins, is intelligent and social.

Conservation note: Risso's dolphin is widespread and generally not of high concern overall, though some populations face pressures such as bycatch. Verify current status at iucnredlist.org and NOAA Fisheries.

Habitat & Range

Risso's dolphins prefer deep waters, especially over the continental slope and around steep underwater features, in temperate and tropical seas around the world. These deep areas concentrate the squid on which they depend.

Diet

Risso's dolphins feed mainly on squid and other cephalopods, along with some fish. They are deep divers, hunting their prey well below the surface, mostly at night when many squid rise toward shallower water.

Behavior

Risso's dolphins usually travel in groups of moderate size and can associate with other dolphin and whale species. They breach, slap the water, and surface roll, and communicate with whistles and clicks while using echolocation to find squid in the dark. The distinctive scarring on their bodies builds up over a lifetime and helps researchers recognise individuals.

Human Interaction & Conservation

Risso's dolphins are seen on whale-watching trips and are mostly affected by accidental capture in fishing gear, pollution, and noise in some regions. For current status and regional context, consult NOAA Fisheries and the IUCN Red List.

Intelligence & Social Complexity

As a member of the dolphin family, Risso's dolphin shares the high intelligence and social nature of its relatives. It lives in coordinated groups, sometimes mixing with other cetacean species, and relies on echolocation and a complex range of calls to hunt squid in deep, dark water and to stay in contact. Its lifestyle — cooperative, communicative, and reliant on sophisticated biosonar — reflects the advanced cognition characteristic of dolphins.

More photos of the risso's dolphin

Risso's dolphin showing its scarred grey skin.

Risso's dolphin (Grampus griseus), showing characteristic scarring.

Image: Kiloueka, CC0, via Wikimedia Commons.

Frequently Asked Questions — Risso's Dolphin

Why is Risso's dolphin so scarred?
The pale, scratched appearance comes from scars that build up over the animal's life — from social interactions with other Risso's dolphins (including tooth rakes) and from struggles with the squid they eat. Because the scars accumulate and don't fully fade, older individuals can look almost white.
What do Risso's dolphins eat?
Mainly squid and other cephalopods, plus some fish. They are deep divers that hunt below the surface, often at night when squid move toward shallower water.
How can you tell a Risso's dolphin from other dolphins?
Look for the blunt, beakless head, the tall dorsal fin, the robust grey body, and especially the heavy network of pale scars — features that together make Risso's dolphin distinctive among dolphins.
Are Risso's dolphins intelligent?
Yes. Like other members of the dolphin family, Risso's dolphins are intelligent and social, using echolocation and complex calls to hunt cooperatively in deep water and to communicate within their groups.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.