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Bottlenose Dolphin

(Tursiops truncatus)

Short Description

The Bottlenose Dolphin is probably the most well known cetacean due to it's entertainment ability in captivity, visibility from shore and from popular children’s shows like "Flipper." Their only natural enemy appears to be the killer whale, although they are more and more impacted by pollution and toxins released into the oceans, the coastal types suffering most.

Most aquariums around the world have bottlenose dolphins in captivity, although with the increased screening of nature films and wildlife documentaries, as well as increased public awareness of conservation issues, they have become less popular centres of entertainment.

Long Description

Size
The dolphin are quite large and grow to between 2.5 and 3.3 metres in length and weigh between 200 and 350 kg. In Southern Africa, two similar forms exist – a smaller coastal type and a deeper water type that is a lot larger and more robust.

Identification
The smaller bottlenose, which is most commonly seen, is dark grey in colour to the midline, lighter around the head and belly area (which is sometimes pink in colour), and adults are often heavily scarred. Scarring is thought to be from territorial, social and mating disputes between adults.

Diet
Bottlenose dolphins have between 18 and 26 pairs of teeth and a diverse diet. They eat fish, squid, eels, and occasionally crustaceans, and like orcas, they have regularly been observed feeding co-operatively on schools of small fish. 

Social Groups and Activity
The bottlenose dolphin  (particularly the coastal variety) are often seen porpoising and surfing in the breakers. They also tend to be co-operative feeders, encircling their prey into tight shoals, maintaining it and taking turns to feed. They are also opportunistic in that in some areas they have taken to following trawlers and other fishing boats to feed on the unwanted fish that are thrown overboard (bycatch). These activities sometimes result in some mortality through entanglement in fishing gear.

They have also been observed beaching themselves up onto mudflats to capture fish in a similar fashion to the killer whale. 

Reproduction
The gestation period of a bottlenose dolphin is about 12 months, after which the female gives birth to a calf about a metre long and 14 kg in weight. The calf continues to suckle for three or four years.

The peak calving period is between spring and summer and most females give birth every 2 to 3 years.

Distribution

Bottlenosed dolphins are prolific all around the world, living in shallow waters generally not more than 30 metres deep, although deeper water species are also common. They are often found in groups of between 10 and 50 individuals, frequently surfing the breakers along the shoreline. They inhabit temperate and tropical waters throughout the world, and usuall stay inshore.
In the Pacific Ocean, they are found from northern Japan and California to Australia and Chile. They are also found offshore in the eastern tropical Pacific as far west as the Hawaiian islands. In the Atlantic Ocean, bottlenose dolphins are found from Nova Scotia and Norway to Patagonia and the tip of South Africa.

They are the most abundant dolphin species along the United States from Cape Cod through the Gulf of Mexico.

They are also found in the Mediterranean Sea, and in the Indian Ocean from Australia to South Africa.

Distribution Map

Bottlenose Dolphin  Distribution Map

Various

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