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Bottlenose Dolphin (Tursiops truncatus)
Description
Colour varies from dark gray at the top near the dorsal fin to very light grey and almost white at the underside. Can be distinguished from the similarly proportioned but smaller common dolphin by the lack of sharper, more distinctive patterning as the bottlenose dolphin's colouration tends to blend from one shade to another more gradually. Elongated upper and lower jaws form a rostrum, or beak-like snout, which gives the animal its common name. The real, functional nose is the blowhole on top of its head.
Behaviour
Being mammals, dolphins must return to the surface to breath and this makes them easy to watch. Playful and active, they can be seen leaping out of the water. Bottlenosed dolphins are social animals which live for most of the year in single-sex groups, though males, females and young live together during the breeding season. They communicate by a series of whistles and clicks, and individuals can clearly recognise and respond to each other. Also use echolocation in the form of a series of loud clicks to form a 'picture' of their surroundings in murky water. When large shoals of fish are encountered they co-operate in the hunt by herding them into a tight mass. At other times when prey is less aboundant they hunt as individuals at night for squid and bottom-dwelling fish and have been known to feed at depths of up to 280m. They can dive to 600m and stay underwater for up to 15 minutes between breaths.
Size
Length: 2.3-3.9m; Weight: 150-275kg. (However while a survey in the Moray Firth, the world's northernmost resident dolphin population, recorded an average adult length of just under 4 m, a survey of a population off the coast of Florida showed an average of only 2.5 m.)
Where to see them
Handa Island. Locations around the Moray Firth
When to see them
Commonly sighted around the British Isles and can be seen all year round
What they eat
Marine animals, mainly fish such as salmon, anchovy, capelin and other inshore fish, but also others such as squid and shrimp.
Status
UK BAP Priority Species
Distribution
Widespread with three subspecies; one in the North Pacific, one in the Atlantic and one in the Red sea. The Atlantic bottlenosed dolphin is common along Atlantic Irish seaboard, Cardigan Bay (West Wales), Moray Firth (NE Scotland), and in the western Channel (Normandy and Brittany coasts), Atlantic coast of Portugal, and in the eastern Mediterranean.
Threats
Fishing nets. Distrubance from boats, in particular sightseeing craft.
Fascinating facts
They are intelligent, social animals, and live for most of the year in single-sex groups, but males, females and young live together during the breeding season. They can live up to 50 years. Bottle-nosed dolphins mate in the spring and summer, and females give birth to single calves about 10-12 months later. Although they are capable of giving birth unaided, two or more 'midwives' often help with the delivery by tugging at the newborn's tail and whistling encouragement. They also protect the vulnerable mother and her calf from sharks.