Common Name: Spinner Dolphin
Stenella spp.: Based on recent genetic studies the genus Stenella will mostly be restructured in the near future.
Size comparison against an average human
Spinner Dolphin range.
General Description: Spinner dolphins are slender with a long thin beak and pointed flippers. Head slopes gently towards the snout. Dorsal fin is falcate but highly variable in shape, and becomes more erect with age. Most individuals have a tripartite colour pattern with a dark grey back and white underbelly and the sides a paler shade of grey. Individual variation in colouration can be seen. Most individuals have a dark stripe extending from the eye to the flipper. Beak tip and lips are dark.
Size: Adults, around 2 m long (males:2.35m). Males maybe larger than females, most adults weigh around 75-80 kg. Calves at birth, 75-80cm long.
Appearance At Sea: The Spinner Dolphin gets its name from its habit of leaping out of the water and spinning longitudinally. Individuals have been counted rolling over seven times before falling back into the water. They are known to bow-ride. Group sizes can range from 30 to several hundreds. They are known to sometimes associate with other dolphin species (e.g. Stenella attenuata; spotted dolphins). Spinner dolphins are frequently found in association with tuna, this can result in entanglement in purse seines.
Found In: The Spinner Dolphin’s distribution is primarily in pelagic zones, though it will wander into shelf waters. They feed on small fish and squid.
Records from India:This is a species caught frequently by fisheries by-catch
|Prior to 1827||Photograph of skull (illustration) from Malabar in the US National Museum files.||De Silva, 1987|
|1976–1980||Ninety-two specimens caught in gillnets off the Calicut coast.||Lal Mohan, 1985|
|19 September 1981||Male specimen caught in gillnet off Calicut.||James & Lal Mohan, 1987|
|1982–1984||A number of observations off the coasts of southern India.||Alling, 1986|
|15 May 1982||One specimen collected at Porto Novo (11º29’N; 79º46’E) in a bottom-set gillnet.||Rajaguru & Natarajan, 1985;
Kumaran & Subramanian,1993
|July 1983–December 1986||18,210 kg of this dolphin landed at Fisheries Harbour, Cochin.||Jayaprakash et al., 1995|
|11 February 1986||One male, 1.9 m long, caught at Bombay High near the ONGC offshore base in a gillnet.||Karbhari et al., 1985|
|5 March 1986||One male, 2.28 m long, caught off Janjira–Murud, Maharashtra in gillnet.||Karbhari et al., 1985|
|29 August 1989||One specimen caught in a gillnet in the Gulf of Mannar.||Krishna Pillai, Bose et al., 1989|
|28 December 1990||Nearly 300 counted at sea, south of Mangalore at 11°46’N, 10°E.||Jayaprakash et al., 1995|
|21 August 1991||One young female entangled in gillnet off Visakhapatnam – this was only 70.5 cm long & 2.66 kg
in weight .
|Seshagiri Rao & Narayana Rao,
|1993 [?]||Two animals entangled in gillnets at the Calicut coast.||Lal Mohan, 1995|
Global Distribution: The species is widely distributed. It is found in all oceans, in tropical, subtropical and warm temperate regions.
Could Be Confused With:The Spinner Dolphin could be confused with the Common Dolphin Delphinus delphis which has a very similar body shape. They can be distinguished based on the following characteristics:
|Spinner Dolphin||Upright or leaning forwards||
|Common Dolphin||Fin leaning backwards||
Diagnostic Features: At sea, tripartite colour pattern, spinning behaviour, and dark-tipped beak.
Stranded Specimens:Spinner Dolphins have 45 to 65 or more sharply pointed teeth in each row. This is the highest tooth-count of any cetacean species.