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Bottlenose dolphins are probably the best known dolphins.
Where they are found
They are found in oceans from temperate (not too hot and not too cold) to tropical (hot and steamy) areas.
In the Atlantic Ocean they are
found from Norway and Nova Scotia to Patagonia and South Africa,
including the Mediterranean Sea. In the Pacific Ocean they are
found from Northern Japan and Southern California to Australia
and Chile. In the Indian Ocean they are found from Australia to
South Africa.
Family
Bottlenose dolphins are cetaceans, the animal group that
includes all whales and dolphins. Dolphins are in the cetacean
family of toothed whales.
Life Cycle
It is thought that bottlenose dolphins live for about 50 years. They are able to mate from about 6 - 8 years of age. Most births are in spring or autumn, although bottlenose dolphins can mate and give birth at any time of year. Females are pregnant for about 12 months.
Dolphin calves are born in the water tail first. This means that the head comes out last, and the calf is taken straight to the surface to breathe.
Calves stay with
their mothers for several years. They feed on milk from their
mother's body for about 3-5 years, although they start eating
small fish when they are about 6 months old.
Diet
Bottlenose dolphins feed on a wide variety of fish, squid, shrimp and small rays and sharks. They sometimes feed alone, but sometimes they work together in a group to catch fish. For example, a group may sometimes chase schools of fish onto mud banks, or they whack fish with their tails to stun them, and sometimes a group circles around a school of fish while one dolphin at a time dives in to feed.
Threats
The main natural predator of bottlenose dolphins is the shark, most often bull sharks, tiger sharks, dusky sharks and great white sharks.
However, humans are generally the greatest threat to bottlenose dolphins in the wild. Dolphins and other marine mammals adapted to live in water millions of years ago, when there were no boats or polluted water, and no competition for fish from humans.
Nowadays people use areas near the shore for fishing, recreation, shipping and other activities.They cause pollution from sewage, poisons and oil spills. Noise occurs from boats, construction, dredging, oil and gas drilling and explosions. All of this affects the environment that marine mammals need for hunting prey and feeding, resting, breeding and socialising. Whales, dolphins and other marine mammals may avoid these areas and may have to use areas where there is less food.
As boat traffic in the oceans increases, so do the threats to
marine mammals. Whale and dolphin watching vessels as well as
commercial and recreational fishing boats can be a danger to marine
mammals. Irresponsible boaters that get too close to dolphins
can scatter groups and put mothers and calves in danger. This
harassment of animals is not allowed but it is hard to catch the
people that do it. 
Many people try to feed the mammals to get them to come closer,
and this can alter their behaviour and make them depend on people
for food instead of hunting for themselves.
Boats coming close to marine mammals also put them in danger from
fishing gear, engine propellers and poison. Dolphins can also
bite and injure human beings that try to hand feed them. They
are after all, wild animals not cute pets.
Did you know?
Since 1847, in Laguna, a town in Brazil, dolphins chase schools of fish into fishermen's nets. They give the fishermen a signal when it is time to throw the nets. The dolphins get a good feed from all the fish that escape the nets, while the fishermen take home a good catch.
Click here to read more about threats to marine mammals from humans
Back to Dolphins and Porpoises
Baleen
whales
.. Blue
whale
.. Humpback
whale..
Toothed
whales
.. Beluga
whale
.. Orca ..
Whale
Strandings...Threats to Marine
Mammals..
If you use any part of this,
acknowledge it in your bibliography like this:
Bottlenose Dolphins
(2002). [Online],
Available: www.kidcyber.com.au
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Updated July 2006