Bottle-nosed dolphin

Bottlenose dolphins, the genus Tursiops, are the most common members of the family Delphinidae, the family of oceanic dolphin. Molecular studies show the genus contains three species: the common bottlenose dolphin (Tursiops truncatus), the Indo-Pacific bottlenose dolphin (Tursiops aduncus), and the Burrunan dolphin (Tursiops australis). Bottlenose dolphins inhabit warm and temperate seas worldwide, being found everywhere except for the Arctic and Antarctic Circle regions. Numerous investigations of bottlenose dolphin intelligence have been conducted, examining mimicry, use of artificial language, object categorization, and self-recognition. They can use tools (sponging; using marine sponges to forage for food sources they normally could not access) and transmit cultural knowledge from generation to generation, and their considerable intelligence has driven interaction with humans. Bottlenose dolphins gained popularity from aquarium shows and television programs such as Flipper. They have also been trained by militaries to locate sea mines or detect and mark enemy divers. In some areas, they cooperate with local fishermen by driving fish into their nets and eating the fish that escape. Some encounters with humans are harmful to the dolphins: people hunt them for food, and dolphins are killed inadvertently as a bycatch of tuna fishing and by getting caught in crab traps. The deepest dive ever recorded for a bottlenose dolphin was 300 meters (990 feet). This was accomplished by Tuffy, a dolphin trained by the US Navy. Nellie, the longest-lived Atlantic bottlenose dolphin in human care, died at age 61 on April 30, 2014. Nellie was born on Feb, 27, 1953 at Marineland. Bottlenose dolphins have the third largest encephalization levels of any mammal on Earth (humans have the largest), sharing close ratios with those of humans and other great apes, which more than likely contributes to their high intelligence and emotional intelligence. Scientists were long aware that the Tursiops dolphins might consist of more than one species. Molecular genetics allowed much greater insight into this previously intractable problem. The IUCN acknowledges two species, although a third distinct species was described in 2011: the common bottlenose dolphin (T. truncatus) is found in most tropical to temperate oceans, and it has a grey color, with the shade of grey varying among populations, but it can be bluish-grey, brownish-grey, or even nearly black, and is often darker on the back from the rostrum to behind the dorsal fin; the Black Sea bottlenose dolphin (T. t. ponticus), a subspecies of T. truncatus lives in the Black Sea; the Pacific bottlenose dolphin (T. t. gillii or T. gillii), another subspecies of T. truncatus, lives in the Pacific, and has a black line from the eye to the forehead; the Indo-Pacific bottlenose dolphin (T. aduncus) lives in the waters around India, northern Australia, South China, the Red Sea, and the eastern coast of Africa, with the back being dark-grey and the belly being lighter grey or nearly white with grey spots;and the Burrunan dolphin (T. australis), found in the Port Phillip and Gippsland Lakes areas of Victoria, Australia, was described in September 2011 after research showed it was distinct from T. truncatus and T. aduncus, but it is not considered a separate species by the IUCN. The two ecotypes of the common bottlenose dolphin within the western North Atlantic are represented by the shallower water or coastal ecotype and the more offshore ecotype. Their ranges overlap, but they have been shown to be genetically distinct. They are not currently described, however, as separate species or subspecies. In general, genetic variation between populations is significant, even among nearby populations. As a result of this genetic variation, other distinct species currently considered to be populations of common bottlenose dolphin are possible. Old scientific data do not distinguish between the two species, making it useless for determining structural differences between them. The IUCN lists both species as data deficient on their Red List of endangered species because of this issue.