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Order : CETARTIODACTYLA
Infraorder : Cetacea
Family : Delphinidae
Species : Tursiops truncatus
Total Length : up to
3.8 metres
Weight : Up to 650 kg
Females are slightly smaller than males.
The Common Bottlenose
Dolphin Tursiops truncatus is the most widespread of the three
species of dolphin in the genus Tursiops. It occurs in all oceans
except cold, polar regions. In Southeast Asia the species is sympatric with
the closely related
Indo-pacific Bottlenose Dolphin Tursiops aduncus (i.e. it occurs
in the same areas and habitats).
T. truncatus is larger than T. aduncus, and the skin color is
a more uniform medium grey : it lacks the speckling which occurs on the
lower flank and belly of T. aduncus. The snout is shorter and
thicker than that of T. aduncus.
Huge groups or 'pods' of this species comprising over 1000 individuals
sometimes occur, but the typical pod size is around 10 to 20 individuals.
Prey items include a variety of fishes, squid and shrimp, which are located
by echolocation. Echolocation comprises a complex series of clicks
emitted underwater in the manner of sonar : the resulting echoes allow the
animal to determine the location, size and trajectory of underwater prey.
The Common Bottlenose Dolphin is the species which is widely exploited for
mindless, human entertainment in oceanariums and aquariums.
The true distribution of this species within the waters of Southeast Asia is
somewhat uncertain, given that historical records may have been sightings of
T. aduncus. Francis (2008) lists Vietnam and Borneo as confirmed
locales.
Fig 1 : Side profile showing the curved dorsal fin.
Fig 2 : Close up of the short, thick snout, which is dark grey on top and
pale beneath.
Fig 3 : Part of a pod of 15-20 dolphins seen off the coast of Cape Jackson,
South Island, New Zealand.
Photos thanks to Ian Prothero
References :
Francis, C.M. 2019. A Field Guide to the Mammals of South-east Asia. Second
Edition. New Holland. 416 pp.
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