Bottlenose Dolphin
(Tursiops truncatus) #66-127

Picture of the Bottle-nose dolphin.

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Physical characteristics and distribution

The Bottlenose Dolphin (Tursiops truncatus) is the most common and well-known dolphin species.

Bottlenose Dolphins are grey, varying from dark grey at the top near the dorsal fin to very light grey and almost white at the underside. The salt water makes them hard to see both from above and below when swimming. The elongated upper and lower jaws give the animals their name of bottlenose. The real nose however is the blowhole on top of the head, and the nasal septum is visible when the blowhole is open. Their face shows a characteristic "smile". Adults range in length from 2 to 4m (6 to 13 feet) and in weight from 150 to 650kg (330 to 1430 pounds) with males being slightly longer and considerably heavier than females on average. The size of the dolphin appears to vary considerably with habitat.

Their diet consists mainly of small fish, occasionally also squid, crabs and similar animals. Their peg-like teeth serve to grasp but not to chew food. When a shoal of fish has been found, the animals work as a team to keep the fish close together and maximize the harvest. They also search for fish alone, often bottom dwelling species. Sometimes they will employ "fish whacking" whereby a fish is stunned (and sometimes thrown out of the water) with the fluke to make catching and eating the fish easier.

The dolphin's search for food is aided by a form of echolocation similar to sonar: they locate objects by producing sounds and listening for the echo. They also have sharp eyesight. Cognitive abilities investigated in the dolphin include concept formation, sensory skills, and the use of mental representation of dolphins.

The gestation period is 12 months. The young are born in shallow water, sometimes assisted by a "midwife" (which may be male). A single calf is born, about 1 meter (3 feet) long at birth. To speed up the nursing process, the mother can eject milk from her mammary glands. The calf is nursed for 12 to 18 months. The young live closely with their mother for up to 6 years; the males are not involved in the raising of their offspring. The females become sexually mature at age 5-12, the males a bit later, at age 10-12.

Its distibution is worldwide: temperate to tropical waters, including the Black Sea.

Description of the brain

Animal source and preparation

This specimen of the Bottlenose Dolphin (Tursiops truncatus) was perfused by formol-saline according to our standard protocol at the end of a long recording experiment in which Dr. Richard Lende and W. Welker were recording from the cerebral cortex using in-depth microelectrodes in search of somatic sensory projections. This was a young adult. The specimen was captured alive by the personnel at Marineland of Florida.

All specimens collected followed the same preparation and histological procedure.

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