Tursiops truncatus

Common Name: Bottlenose Dolphin

Bottlenose Dolphin
Bottlenose Dolphint

Bottlenose Dolphin breaching in the bow wave of a boat

Bottlenose dolphin size.svg

Size comparison against an average human

Conservation Status
bottlenose Status iucn3.1 blank.svg

Data Deficient (IUCN 3.1)

Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Mammalia
Subclass Eutheria
Order Cetacea
Suborder Odontoceti
Family Delphinidae
Genus Tursiops
Species T. truncatus
Binomial Name
Tursiops truncatus
(Montagu, 1828)

bottlenose Cetacea range map

Bottlenose Dolphin range.

Source: Wikipedia

General Description: The head and trunk are robust, slimming behind the dorsal fin. The snout is clearly demarcated from the bulbous forehead by a sharp crease. The beak of this large dolphin is usually short and stubby. The lower jaw protrudes conspicuously beyond the upper. The dorsal fin is moderately tall and triangular or sickle shaped. The flippers are somewhat long.

The colouration is variable, but usually dark grey on back, lighter grey on the flanks, grading to white or pink on the belly. Some specimens have spots on them. Adult dolphins may also have a white mark on the tip of the lower jaw.

Calves have a slightly bluish colouration.

bottlenose

Size: Adults, Bottlenose Dolphin males grow to 4 m in length, and females to 3.6 m. The weight of these dolphins varies greatly, from 90 to 650 kg, though it is said that the greatest weight reliably recorded is 275 kg. Calves at birth, 1 m long.

Appearance At Sea: This is the species of dolphin best known to the general public, as a result of exhibition in dolphinaria and films and television. It is also apparently strongly attracted to human activities.

Bottlenose Dolphin groups cooperate and communicate between themselves when hunting for food. They have been observed using the geography of inland waters to create fish traps. They eat most fish they can catch. Bottlenoses are hunted with guns and harpoons in many parts of the world. The numbers being captured for live display constitutes a threat to the species now.

bottlenose1

The Bottlenose Dolphin is found in small herds that sometimes gather into much larger schools. They often school with other species including Shortfin Pilot Whales Globicephala macrorhyncus, and can be seen in the company of Great Right Whales Balaena glacialis and Humpback whales Megaptera novaeangliae on their migrations.

There are a number of instances in which Bottlenose Dolphins have displayed mutual assistance and support. In cooperative defence, they may ram large sharks with their beaks or heads. The impact could be great enough to lift the fish out of the water.

Bottlenose Dolphins can reach speeds of 25 kilometres per hour.

Found In: There are two forms of this dolphin, one coastal and the other offshore. The species may be found in depths from 15 to 1000 m or more. They feed mainly on bottom-dwelling fish, but will also take eels, catfish, rays, hermit crabs, shrimps, mullet, and pelagic fish.

Records from India: This is one of the commonest species of India. The many records are mostly of specimens caught in fishing nets. The Bottlenose Dolphin is said to make up 14 percent of the dolphins landed in Indian coasts.

DateDetailsReferences
1846 [?] Skull from Bay of Bengal, the type of “Delphinus eurynome”, in the British Museum
(Natural History).
De Silva, 1987
[?] Four skeletons from Trivandrum in the British Museum (Natural History). De Silva (1987)
1848 [?] “Delphinus perniger” described by Elliot from the Bay of Bengal; Stuffed skin in
the Museum of the Asiatic Society, Calcutta.
Jerdon, 1867; De Silva (1987); Corbet & Hill (1992)
1982­–1984 A number of observations off the coasts of southern India. Alling, 1986
1866 [?] “Delphinus godama” described by Owen from collections made by Sir Walter Elliot
near Visakhapatnam; The skull gifted by Elliot to the British Museum (Natural History) .
Jerdon, 1867; De Silva, 1987
14 February 1901 One specimen “Tursiops fergusoni” measuring 2.4m (8 feet 1 inch) brought by
fishermen to Trivandrum.
Ferguson, 1903
7 March 1901 [?] One specimen “Tursiops catalania” measuring 2.2m (7 feet 4.5 inches) stranded at
Trivandrum.
Lydekker, 1904
15 October 1903 A pair taken off the Trivandrum coast. Lydekker, 1905
October 1904 Specimen caught off Trivandrum may be this species. Lydekker, 1905
1904 A single specimen of “Tursiops gilli” obtained from Travancore. Pillay, 1926
February 1908 Two specimens of “Tursiops dawsoni” purchased measuring 2.7 & 2.8 m (9 feet &
9 feet 4 inches) by the Trivandrum museum; one skeleton in the British Museum
(Natural History).
Pillay, 1926; De Silva, 1987
1976–1980 Fifty-seven animals caught off Calicut coast in gillnets. Lal Mohan, 1985
21 December 1978 One male caught off Calicut. James & Lal Mohan, 1987
12 November 1980 One male measuring 1.83 m caught near Krusadi Island in a trawl net. Krishna Pillai & Kasinathan, 1987
1 December 1980 One female with a foetus caught in a gillnet off Calicut. Lal Mohan, 1982
31 January 1981 Female with a foetus in a gillnet off Calicut. Lal Mohan, 1982
26 November 1981 Adult female caught in the Gulf of Mannar near Mandapam. Krishna Pillai & Kasinathan, 1987
8 December 1981 Young female measuring 1.43 m caught in trawl net near Mandapam. Krishna Pillai & Kasinathan, 1987
1981–1982 Stray numbers landed at Fisheries Harbour, Cochin at certain months; along with
Common Dolphins made up 1% of the total gillnet landings.
Silas et al., 1984
25 March 1982 One collected at Porto Novo in a bottom-set gillnet . Rajaguru & Natarajan, 1985; Kumaran & Subramanian, 1993
7 December 1982 Seven dolphins following the net during trawling operations near Krusadai Island. Krishna Pillai & Kasinathan, 1987
15 December 1982 15-30 dolphins following the end of the net in during trawling operations in the vicinity of
Krusadi Island.
Krishna Pillai & Kasinathan, 1987
1982–1984 A number of observations off the coast of India. Alling, 1986
July 1983–December 1986 10,489 kg of this species landed at Fisheries Harbour, Cochin. Jayaprakash et al., 1995
28 January 1985 One washed ashore near Krusadi Island. Krishna Pillai & Kasinathan, 1988
[?] One male caught 30 km south of Visakhapatnam during shrimp trawl operations. Seshagiri Rao & Narayana Rao, 1993
13 April 1992 Female calf 1.07 m long and weighing 10.5 kg caught off Gopalpur and landed at Vizag
Fisheries Harbour identified as a Bottlenose Dolphin.
Chandrasekar et al., 1993
28 April 1993 Female caught in a bottom-set gillnet about 30 km northeast of Kakinada. Nageswara Rao & Venkata Raman, 1994
1993 [?] One male entangled in gillnets at the Calicut coast. Lal Mohan, 1995
9 January 1995 One carcass found near Mandapam. Lipton et al., 1995
11 November 1995 One washed ashore at Digha fish landing centre, Midnapore district, West Bengal. Kar, 1996
7 July 1997 One female Bottlenose of length 2.45 m caught off Kakinada. Venkataramana & Achayya, 199

World Distribution: The species is widely distributed in warm and temperate waters. It is found in all oceans, in all regions but the high latitudes.

Could Be Confused With:The Bottlenose Dolphin might be confused with other species which are predominantly blue or grey, like the Rough-toothed Dolphin Steno bredanensis and the Spotted Dolphins Stenella spp. They can be distinguished based on the following characteristics:

SpeciesSizeBuildBeakMarkings
Bottlenose Dolphin Average size 3m, often more Bulky Short beak, clearly marked off from melon No spots
Rough-toothed Dolphin Seldom more than 2.4 m Slender Long thin beak, not clearly demarcated from
forehead
Irregular blotches on belly
Spotted Dolphin Around 2.4 m Slender Longish beak, well demarcated from melon Many regular spots

Diagnostic Features: At sea, stout body, short beak, moderately tall dorsal fin.

Stranded Specimens:Beached individuals can be readily recognized by their stubby beaks and robust bodies. There are 18 to 26 pairs of relatively large teeth in each jaw.

Note:Bottlenose Dolphin recorded from India recently have been identified as Tursiops aduncus. This raises the possibility that previous records of Tursiops truncatus are misidentifications.