The Bottlenose Dolphin - the most common and well-known dolphin - is grey, varying from dark grey at the top near the dorsal fin to very light grey and almost white or maybe even a pinkish colour at the underside. This makes it harder to see both from above and below when swimming. The elongated upper and lower jaws form what is called the rostrum, which gives the animal the name bottlenose. The real nose, however, is the blowhole on top of its head, and the nasal septum is visible when the blowhole is open. Its face shows a characteristic "smile". The "smile" does not mean that it is happy; it is unable to move its jaw to any other position.
It inhabits warm and temperate seas worldwide and may be found in all but the Arctic and the Antarctic Oceans.
Adults range in length from 2 to 4 metres (6 to 13 ft) and in weight from 150 to 650 kilograms (330 to 1430 lb); however, in most parts of the world, the adult's length is about 2.5 m (8 ft) and adult weight ranges from 200 to 300 kg (440 to 660 lb), with males being slightly longer and considerably heavier than females, on average.
The size of the dolphin appears to vary considerably with habitat. Research showed that dolphins in warmer, shallower waters tend to have a smaller body than their cousins in cooler pelagic waters. Those in colder waters also have a fattier composition and blood more suited to deep-diving
The flukes (lobes of the tail) and dorsal fin are formed of dense connective tissue and don't contain bones or muscle. The animal propels itself forward by moving the flukes up and down. The pectoral flippers (at the sides of the body) are for steering; they contain bones clearly homologous to the forelimbs of land mammals (from which dolphins evolved some 50 million years ago). In fact, recently, a Bottlenose Dolphin was discovered in Japan that has two additional pectoral fins, or "hind legs," at the tail, appearing to be about the size of a human's pair of hands. Scientists believe that a mutation must have caused the ancient trait to reassert itself.
Every 5-8 minutes, the Bottlenose Dolphin, like all other dolphins, needs to rise to the surface to breathe through its blowhole, though it generally breathes more frequently - up to several times per minute. Its sleep is thus very light; some scientists have suggested that the two halves of its brains take turns in sleeping and waking. It has also been suggested that it has tiny periods of 'microsleep'.
The Bottlenose Dolphin normally lives in groups called pods, usually containing up to 12 animals. These are long-term social units. Typically, a group of adult females and their young live together in a pod, and juveniles in a mixed pod. Several of these pods can join together to form larger groups of one hundred dolphins or more. Males live mostly alone or in groups of 2-3 and join the pods for short periods of time.
Dolphins - commonly known for their friendly character and curiosity towards humans immersed in or near water - are predators however, and they also show aggressive behaviours. This includes fights among males for rank and access to females, as well as aggression towards sharks, certain (but not all) Orcas, and other smaller species of dolphins. Male dolphins, during the mating season, compete very vigorously with each other through showing toughness and size with a series of acts such as head butting. At least one population, off Scotland, has been observed to practice infanticide, and has also been filmed attacking and killing Harbour Porpoises.
Female Bottlenose Dolphins live for about 40 years, whereas males rarely live more than 30 years.
Source: Wikipedia
* Bottlenose Dolphins Infobook at
Seaworld.org
* MarineBio
Bottlenose Dolphins
* Adopt a dolphin at
Blue-World.org
* Project to protect the natural habitat of dolphins at
The Nature Conservancy
* Dolphin
Pictures
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National Geographic for kids
*
The Bottlenose Dolphin Research Institure
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The National Parks Conservation Association
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WDCS
