Common Name: Spinner Dolphin
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: Spinner solphins gets the 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: Spinner dolphins are distributed primarily in pelagic zones, though they 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 . Seen commonly offshore in peninsular India and both island systems of Lakshadweep and Andaman Nicobar.
Global Distribution: The species is widely distributed. It is found in all oceans, in tropical, subtropical and warm temperate regions.
Could Be Confused With: Common dolphins and other small Stenella
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.