Dolphins are found in shallow waters near continental shelves throughout the world’s oceans. Some species inhabit rivers in China, India and South America. Dolphins mainly eat fish, squid and shrimp. Their average lifespan varies by species, but bottlenose dolphins can live up to 50 years in captivity.
- Scientific & Common Names
- Present Status
Scientific & Common Names
Species: T. truncatus, T. aduncus, T. australis
Common Name: Bottlenose Dolphin. It was once thought that there was only one species of this type of dolphin, but recent genetic studies have revealed three distinct species: the Common (truncatus), the Indo-Pacific (aduncus) and the Burrunan (australis).
Dolphins have a sleek build that helps them swim fast. Most species, including bottlenose dolphins, are gray in color and have lighter bellies. Their heads have an organ called a melon, which is used for echolocation, and a large brain. Some dolphin species have a prominent beak, while others have a shorter one. All species have blowholes, tail fins, pectoral fins and dorsal fins. Adult dolphins vary in size, depending on the species. Killer whales are the largest species, with adults measuring around 25 feet long and weighing around 19,000 pounds. Hector’s dolphins are the smallest species, with adults measuring about 4.5 feet long and weighing around 110 pounds.
Bottlenose dolphins can grow to be up to 13 feet in length, though the Indo-Pacific and Burrunan species are considerably smaller.
Dolphins breed throughout the year, but peak breeding typically occurs during the warmer months. The gestation period of female dolphins varies by species. For example, Peruvian river dolphins gestate for about 11 or 12 months, while killer whales gestate for around 17 months. Female dolphins usually produce one calf at a time, and they provide most of the parental care for their young, including nourishment and protection from predators.
Dolphins are known for being curious, playful and intelligent. They are also very social, and they live in pods that vary in size, depending on the species. Dolphins use vocalizations, such as clicks and whistles, as a form of communication. They also use physical contact and posturing to communicate with other dolphins. While some dolphins are aggressive toward other members of their species, others have been known to assist other species, such as pilot whales.
Dolphins descended from land-dwelling mammals that moved to water around 55 million years ago. In more recent times, dolphins have been used by the military for search and rescue purposes and to find mines. They have also been used as therapy animals, and many are still kept in marine parks.
Most dolphin species are listed as “Least Concern,” but Hector’s dolphin and the Ganges River Dolphin are endangered. The Baiji dolphin is listed as critically endangered and may even be extinct, and a few other species are vulnerable or near threatened. The main threats dolphins face include pollutants, boat collisions and accidental capture by fishing nets. Conservation measures include legal protection from wildlife trade and the use of safer fishing nets.
Bottlenose dolphins are very widespread and highly adaptable, so they are in no current danger of extinction. However, they are hunted in certain parts of the world, and are occasionally captured in nets as they tend to travel alongside tuna schools. Chemicals produced by humans may also be affecting the health of bottlenose dolphins.
- <a href="http://animaldiversity.ummz.umich.edu/accounts/Tursiops_truncatus/" target="_blank">http://animaldiversity.ummz.umich.edu/accounts/Tursiops_truncatus/</a>
- <a href="http://animals.nationalgeographic.com/animals/mammals/bottlenose-dolphin/" target="_blank">http://animals.nationalgeographic.com/animals/mammals/bottlenose-dolphin/</a>
- <a href="http://www.defenders.org/dolphin/basic-facts" target="_blank">http://www.defenders.org/dolphin/basic-facts</a>
- <a href="http://www.iucnredlist.org/details/12119/0" target="_blank">http://www.iucnredlist.org/details/12119/0</a>
- <a href="http://www.iucnredlist.org/details/22563/0" target="_blank">http://www.iucnredlist.org/details/22563/0</a>