Stenella longirostris

Common Name: Long-Snouted Spinner Dolphin

Spinner Dolphin
Longsnout Spinner dolphin jumpingt
Longsnout Spinner dolphin size.svg

Size comparison against an average human

Conservation Status
longsnoutsnipper Status iucn3.1 blank.svg

Data Deficient (IUCN 3.1)[2]

Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Mammalia
Subclass Eutheria
Order Cetacea
Suborder Odontoceti
Family Delphinidae
Genus Stenella
Species S. longirostris
Binomial Name
Stenella longirostris
(Gray, 1828)

longsnout Cetacea range map

Spinner Dolphin range.

Source: Wikipedia

General Description: The Spinner Dolphin (or the Long-beaked Porpoise) is a particularly slender dolphin with a long, thin beak, and flippers which are large and pointed. Its head slopes gently towards the snout. There is however, a well-defined crease at the junction of the melon and the beak. The dorsal fin is sickle-shaped and becomes more erect with age.

The back is dark, and the belly white, with a band of intermediate pale grey separating the two. There is individual variation, and like the Maharashtra specimens some may be uniformly dark grey in colour. Still others may be grey with a white belly. Most have a dark stripe from the eye to the flipper, and dark lips and beak tip.

longsnoutspinner

Size: Adults, around 2 m long. They weigh about 75 kg, but two specimens caught off Maharashtra weighed 128 and 148 kg. Calves at birth, 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.

Spinner Dolphins will often bow-ride. They are found in small to very large groups.

The usual social unit is a large school of thirty to several hundred dolphins of all ages and sexes.Sometimes they mix with schools of other dolphins.

longsnoutsnipper1

Like Spotted Dolphins Stenella attenuata, Spinner Dolphins are frequently found in association with tuna. Fishermen in the Pacific herd the dolphins, along with the tuna, and catch them together. The dolphins are not always successfully released and many die.

Spinner Dolphins produce a range of click sounds, pulse bursts and squeals.

Found In: The Spinner Dolphin’s distribution is primarily in pelagic zones, though it will wander into shelf waters. It feeds on small fish and squid.

Records from India:This is a species caught frequently by fisheries. Spinner Dolphins are reported to form more than 44 percent of the dolphin catches on the west coast of India.

DateDetailsReferences
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,
1992
1993 [?] Two animals entangled in gillnets at the Calicut coast. Lal Mohan, 1995

There are records including sightings and catches of the species from Sri Lanka, the Maldives, Djibouti, Somalia, the Gulf of Oman, Gulf of Aden and the Red Sea.

World 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.

SpeciesFinMarkings
Spinner Dolphin Upright or forward-leaning fin
  • Dark stripe from the eye to the flipper;
  • Dark lips and beak tip
Common Dolphin Backward-leaning fin
  • Hourglass pattern of yellow on side;
  • Dark stripe from flipper to chin

There is also a possibility of confusion with the Spotted Dolphin and the Bridled Dolphin which often school with Spinner Dolphins, but the Spinner Dolphin’s dark-tipped beak helps in distinguishing it from these species which have light-tipped beaks.

Diagnostic Features: At sea, Upright or forward-leaning fin, grey back and dark-tipped beak.

Stranded Specimens:Spinner Dolphins have 45 to 65 or more sharply pointed teeth in each row. This is the largest number of teeth found in any cetacean.