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Risso's Dolphin

Grampus griseus

Not yet photographed by the community

Blunt head; older adults almost completely white-scarred.

Species Profile

Least Concern (IUCN); not assessed on UK Red List but population trends stable globally

Lifespan: 35–40 years in the wild
Size & Weight: 3.5–3.8 m in length; 300–500 kg
Habitat: Deep offshore waters and continental shelf edges, typically in waters deeper than 200 m.
UK Distribution: Irregularly found in UK waters, particularly in south-western approaches and Celtic Sea; more common in summer months as a non-resident visitor.
Diet: Deep-diving squid and fish, particularly mesopelagic prey species found at depth.
Prey: Squid (particularly Teuthida species), lanternfish, and other deep-sea fish
Predators: Orcas (killer whales) and large sharks; calves vulnerable to other cetaceans
Mating Season: Year-round with peaks in summer months
Breeding: Single calf born after 13–14 month gestation period; calves nurse for 1–2 years; breeding interval of 2–4 years
Behaviour: Highly social dolphins forming groups of 5–50 individuals, sometimes aggregating into larger schools. They are deep divers reaching depths of 500+ m and are known for their acrobatic surface behaviour. Risso's dolphins are relatively vocal, using clicks and whistles for echolocation and communication.

Did You Know?

•Named after Antoine-Risso, an 18th-century naturalist from Nice, France
•Adults develop distinctive white scars and rake marks on their skin from teeth rakes during social interactions
•They can dive to depths exceeding 600 m in search of deep-sea squid
•Risso's dolphins have an unusually robust head with a pronounced melon and no beak
•They are among the deepest-diving cetaceans in UK waters and are rarely observed at the surface

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