- 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.