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.