Risso's dolphins live in small groups of about ten individuals. The groups move to warm tropical waters in winter and head back toward the poles in summer. The dolphins are often seen leaping out of the water as members of a school play with one another.
Risso's dolphins feed in deep water. They dive down to catch fast-swimming squid and fish. Like other dolphins, they probably use echolocation to locate their prey in the dark depths. They produce clicking noises that bounce off objects in the water. The dolphins can hear each other's clicks and echoes, and groups may work together to track down shoals of fish or squid. In areas where there is plenty of food, dolphin schools congregate, so that thousands of the leaping mammals may be seen together.
Risso's dolphins have very blunt faces, lacking the beaks of typical dolphins. They have dark grey bodies, which are often scarred by attacks from other dolphins and large squid. Older dolphins may have so many scars that their bodies look almost white.
Not much is known about the breeding habits of this species. Most births take place in the warmer summer months.
Distribution: All tropical and temperate seas. Enters the Mediterranean and Red Seas, but is absent from the Black Sea. This species is not common in the South Atlantic.
Habitat: Deep ocean water.
Food: Fish and squid and occasionally octopus.
Size: 3.6 - 4 m (11.75 - 13 ft); 400 - 450 kg (880 - 990 lb).
Breeding: Single young born once a year.
Life span: 30 years.