SPECIES SUMMARY PAGE

Grampus griseus - Risso's dolphin:

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Summary Information
Living Organisms / Animalia / Craniata / Mammalia / Cetacea / Delphinidae / Grampus / Species
Alternative Names
  • Delphinus griseus Cuvier, 1812; Brest, France.
  • Grampus cuvieri Gray, 1846; Isle of Wight, England.
Description Large robust dolphin with blunt rounded head, slight melon and no beak; greyish with many scars on back. Dorsal fin central along back, tall sickle-shape (B142, D23).

Weight:

Length:

  • 3-3.5m / 9-12ft (D23)
  • About 3.3-3.8m, with male slightly larger than female (B142).
  • Neonate: about 150cm (B142).

External Appearance:

  • Body shape: stout torpedo shape, narrows caudal to dorsal fin, to quite narrow tail stick.
  • Head: slight melon, blunt rounded snout with no beak. Deep "V"-shaped furrow in forehead area (visible only close up). Dark to light grey, paler when older: head may be white in old animals.
  • Teeth: lower jaw only, peg-like, often worn, 2-7 per jaw.
  • Dorsal and flanks: dark to light grey. Paler in older animals. Numerous conspicuous white scars on flanks. Abdomen while, enlarging to oval/anchor-shaped patch on chest and chin.
  • Flippers: long (1/6 of body length), pointed, usually dark.
  • Dorsal fin: central along back, tall sickle shape, taller and more erect in adult males, dark but (particularly leading edge) paler in older animals.
  • Tail: tail stock quite narrow, flukes with median notch, concave trailing edge, dark.
  • (B142)
  • Neonate: Light grey, changing to chocolate brown as juveniles (B142).
Range and Habitat World: All seas, mainly temperate (B51); tropical to temperate waters (B142).
  • In North-eastern Atlantic: north to Northern Isles of Scotland.
  • British & Irish waters: Wide distribution in coastal waters, mainly on Atlantic seaboard, also northern North Sea. Rare/absent in English channel, rare/absent in central and southern North Sea. Mainly seen within 10km of land.

Movement:

  • Most likely to be seen from Britain in summer, particularly August/September - may be movement towards coast at this time (B142).

Habitat: --

Further Information Food: Mainly:
  • Squid (Todarodes, Loligo, Gonatus, Histioteuthis spp.)
  • Octopus (Eledone spp.).
  • Cuttlefish (Sepia spp.)

Also fish (Gadus spp.)

(B142)

Feeding Behaviour: --

Breeding:

  • Births probably mainly early spring to summer.
  • (B142).

Breeding Behaviour:

  • Probably polygynous (B142).

Activity:

  • Usually swim at about 10-12 km/hour, but can reach 25-30 km/hour (B142).
  • Younger animals most likely to breach from water (B142).

Social Behaviour:

  • Small herds, often less than 10 individuals but not uncommonly 10-30, rarely larger (B142).
  • Usually only one mature male in group, plus several adult females and juveniles (male and female)

Organisations (UK Contacts):

Electronic Library (further reading):

General Legislation:

Individual techniques:

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