Stenella attenuata

Common Name: Spotted Dolphin

Pantropical Spotted Dolphin
spotteddolphint

Dolphin skipping on its tail over the water.

spotted dolphin size.svg

Size comparison against an average human

Conservation Status
spotteddolphin Status iucn3.1 LC.svg

Least Concern (IUCN 3.1)[2]

Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Mammalia
Subclass Eutheria
Order Cetacea
Suborder Odontoceti
Family Delphinidae
Genus Stenella
Species S. attenuata
Binomial Name
Stenella attenuata
(Gray,1846)

spotteddolphin Cetacea range map

Pantropical Spotted Dolphin range.

Source: Wikipedia

General Description: The Spotted Dolphin (also called the Pantropical Spotted Dolphin) has a beak that is moderately long, and a tall, falcate dorsal fin which is centrally placed.

Newborn Spotted Dolphins are unspotted, having a dark grey back with soft edges and a light belly. Adult Spotted Dolphins are grey overall, darker above and on the upper flanks, and lighter on the belly and lower flanks. The body is usually spotted, with white spots above and dark spots below. The spotting increases with age.

There is a distinct dark grey cape, from the head to the dorsal fin. A black circle around the eye extends to the junction of the beak and the melon, and a broad black stripe runs from the origin of the flipper to the corner of the mouth. Due the presence of a distinct bridle it is also known as the Bridled Dolphin.

Coastal forms are generally larger and more heavily spotted than those which live offshore.

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Size: Adults, around 2 m long, weigh around 110 kg.Calves at birth, 90cm long.

Appearance At Sea: The sizes of Spotted Dolphin schools vary from a few individuals to thousands. There appears to be no segregation based on age or sex. Individual dolphins regularly come to the bows of vessels in the ocean.

Spotted Dolphins often throw themselves out of the water, high into the air.

They school with other species of dolphins like Spinner Dolphins Stenella longirostris. For unknown reasons, tuna congregate below such schools. The Spotted Dolphin has suffered the most from incidental kills in purse-seine tuna nets. When caught along with tuna in a net, the dolphins thrash about at first and then get into a sort of stupor. They simply sink tail first into the folds of the net, where they lie until they are pulled out or drown.

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Found In: Spotted Dolphins are found in tropical oceans with warm surface temperatures, both in coastal and offshore regions. They are surface feeders, feeding on various species of fish and squid.

Records from India: There are few records of this dolphin compared with the other members of the genus Stenella occurring in Indian waters.

Date Details References
1846 Described as Steno attenuatus by Gray from the Bay of Bengal. De Silva, 1987
[?] Recorded as Delphinus malayanus by Blanford from the Sundarban Islands. De Silva, 1987
1900 Described as Prodelphinus attenuatus by Beddard from the Bay of Bengal. De Silva, 1987
[?] Skull collected by Mrs. Ince, in the British Museum. De Silva, 1987
1982-1984 One observed bow-riding at night off the coast of India. Alling, 1986
13 April 1983 Sighting in the northern Bay of Bengal. De Silva, 1987
6 August 1999 A group of 12 dolphins including Spotted and Spinner Dolphins stranded 10 km from Tuticorin rescued;
On 9 August 1999, four dead dolphins believed to be members of this group were washed ashore
near the Roche Park area, Tuticorin.
Anonymous, 1999

There are sight records of Spotted Dolphins from various places on the Indian Ocean margin including the Maldives, Sri Lanka, the Seychelles, Oman, Djibouti and Somalia.

World Distribution: These dolphins are widely distributed in tropical and some warm temperate waters around the world. Spotted Dolphins are distributed in a band of varying width around the equator.

Could Be Confused With: Even at a distance the spotting on the dolphins is usually evident, making it easy to identify the species. They are sometimes confused with other spotted species like Stenella plagiodon.

Species Body Colour of Back Bridle Flipper Line
Stenella attenuata Slender Uniform dark cape without flank Marked bridle Dark flipper line
Stenella plagiodon More robust Lighter, more spotted back, bright blaze on flank beneath the fin No bridle Faint flipper line

Young spotted dolphins, prior to the appearance of spots, can be confused with Common Dolphins and Spinner Dolphins, but both these species have longer, darker beaks.

Diagnostic Features: At sea, the unique facial markings (presence of a marked bridle), uniform dark cape on the dorsal side, and presence of a dark flipper line help in identifying the species.

Stranded Specimens:Freshly beached Spotted Dolphins can be identified by their markings alone. Spotted Dolphins have 35-40 tiny pointed teeth on each side of both slender jaws.