Common Bottlenose Dolphin
Encyclopedia
Tursiops truncatus, commonly known as the Common Bottlenose Dolphin, is the most well-known species from the family Delphinidae.
Common bottlenose dolphins are the most familiar dolphins due to the wide exposure they receive in captivity in marine parks, dolphinarias, in movies, and television programs (for example Flipper). T. truncatus are the largest species of the beaked dolphins. They inhabit temperate and tropical oceans throughout the world, and are absent only from polar waters. The bottlenose dolphins previously known as T. truncatus, but recently the genus has been split into two, T. truncatus and T. aduncus. Although this species has been traditionally called the Bottlenose Dolphin, many authors have used the name Common Bottlenose Dolphin for this species since a second bottlenose dolphins species, the Indo-Pacific Bottlenose Dolphin
, was described. The Common Bottlenose Dolphins inhabit warm
and temperate
seas worldwide. Considerable genetic variation has been described among members of this species, even between neighboring populations, and so many experts believe that there may be multiple species included within Tursiops truncatus.
on the top of their head. Their neck is more flexible than other dolphins' due to 5 of their 7 vertebrae not being fused together as is seen in other dolphin species.
The Common Bottlenose Dolphins live in groups called pods that typically number about fifteen dolphins, but group size varies from solitary bottlenose dolphins up to groups of over 100 or even occasionally over 1000 animals. Their diet consists mainly of eels, squid, shrimp and wide variety of fishes. They do not chew their food, instead swallowing it whole. Dolphin groups often work as a team to harvest schools of fish, but they also hunt individually. Dolphins search for prey primarily using echolocation
, which is similar to sonar. They emit clicking sounds and listen for the return echo to determine the location and shape of nearby items, including potential prey. The Common Bottlenose Dolphins also use sound for communication. Sounds used for communication include squeaks and whistles emitted from the blowhole
and sounds emitted through body language, such as leaping from the water and slapping their tails on the water. Their head contains an oily substance to protect the brain case and to act as an acoustic lens.
events.
. They have also been trained for military uses such as locating sea mines or detecting and marking enemy divers, as for example in the U.S. Navy Marine Mammal Program
. In some areas they cooperate with local fishermen by driving fish toward the fishermen and eating the fish that escape the fishermen's nets.
Some interactions with humans are harmful to the dolphins. In the town of Taiji, Japan some 23,000 are hunted for food annually. Also, the dolphins are sometimes killed inadvertently as a bycatch
of tuna fishing.
), since they have an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
The species is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS
), the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS
), the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU)and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia ( Western African Aquatic Mammals MoU).
Common bottlenose dolphins are the most familiar dolphins due to the wide exposure they receive in captivity in marine parks, dolphinarias, in movies, and television programs (for example Flipper). T. truncatus are the largest species of the beaked dolphins. They inhabit temperate and tropical oceans throughout the world, and are absent only from polar waters. The bottlenose dolphins previously known as T. truncatus, but recently the genus has been split into two, T. truncatus and T. aduncus. Although this species has been traditionally called the Bottlenose Dolphin, many authors have used the name Common Bottlenose Dolphin for this species since a second bottlenose dolphins species, the Indo-Pacific Bottlenose Dolphin
Indo-Pacific Bottlenose Dolphin
The Indo-Pacific bottlenose dolphin is a species of bottlenose dolphin. The Indo-Pacific bottlenose dolphin grows to long, and weigh up to . It lives in the waters around India, northern Australia, South China, the Red Sea, and the eastern coast of Africa. Its back is dark grey and its belly...
, was described. The Common Bottlenose Dolphins inhabit warm
Warm
Warm or WARM can refer to:* A somewhat high temperature.* WARM , a radio station licensed to Scranton, Pennsylvania, United States* WARM-FM, a radio station licensed to York, Pennsylvania, United States...
and temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
seas worldwide. Considerable genetic variation has been described among members of this species, even between neighboring populations, and so many experts believe that there may be multiple species included within Tursiops truncatus.
Description
The Common Bottlenose Dolphins are grey in color and may be between 2 and 4 m (6.6 and 13.1 ft) long, and weigh between 150 and 650 kg (330.7 and 1,433 lb). Males are generally larger and heavier than females. In most parts of the world the adult's length is between 2.5 and 3.5 m (8.2 and 11.5 ft) with weight ranges between 200 and 500 kg (440.9 and 1,102.3 lb). Newborn Common Bottlenose Dolphins are between 0.8 and 1.4 meters long and weigh between 15 and 30 kilograms. The common bottlenose dolphins have a short and well-defined snout, that looks like an old-fashioned gin bottle, which is the source for the common name, Bottlenose Dolphin. Like all whales and dolphins, though, the snout is not a functional nose; rather, the functional nose is the blowholeBlowhole (biology)
In biology, a blowhole is the hole at the top of a cetacean's head through which the animal breathes air. It is homologous with the nostril of other mammals. As whales reach the water surface to breathe, they will forcefully expel air through the blowhole. Not only is air expelled, but mucus and...
on the top of their head. Their neck is more flexible than other dolphins' due to 5 of their 7 vertebrae not being fused together as is seen in other dolphin species.
Behavior
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
, which is similar to sonar. They emit clicking sounds and listen for the return echo to determine the location and shape of nearby items, including potential prey. The Common Bottlenose Dolphins also use sound for communication. Sounds used for communication include squeaks and whistles emitted from the blowhole
Blowhole
Blowhole may refer to:*Blowhole , the hole at the top of a whale's or other cetacean's head*Blowhole , a hole at the inland end of a sea cave*Blowhole Diversion Tunnel in Victoria, Australia...
and sounds emitted through body language, such as leaping from the water and slapping their tails on the water. Their head contains an oily substance to protect the brain case and to act as an acoustic lens.
Distribution
T. truncatus can be found in the warm and temperate tropical oceans worldwide. Some populations of the Common Bottlenose Dolphin live closer to the shore (inshore populations) and others live further out to sea (offshore populations). Generally, offshore populations are larger, darker, and have proportionally shorter fins and beaks. Offshore poulations can migrate up to 4200 kilometres (2,609.8 mi) in a season, but inshore populations tend to move less. However, some inshore populations make long migrations in response to El Niño-Southern OscillationEl Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
events.
Intelligence
T. truncatus have a bigger brain than humans. There have been numerous investigations of Common Bottlenose Dolphin intelligence, including tests of mimicry, use of artificial language, object categorization, and self-recognition. This intelligence has driven considerable interaction with humans. The common bottlenose dolphins are popular in aquarium shows and television programs such as FlipperFlipper (1964 TV series)
Flipper, from Ivan Tors Films in association with Metro-Goldwyn-Mayer Television, is an American television program first broadcast on NBC from September 19, 1964, until April 15, 1967. Flipper, a bottlenose dolphin, is the companion animal of Porter Ricks, Chief Warden at fictional Coral Key Park...
. They have also been trained for military uses such as locating sea mines or detecting and marking enemy divers, as for example in the U.S. Navy Marine Mammal Program
U.S. Navy Marine Mammal Program
The U.S. Navy Marine Mammal Program is a program administered by the U.S. Navy which studies the military use of marine mammals—principally Bottlenose Dolphins and California Sea Lions—and trains animals to perform tasks such as ship and harbor protection, mine detection and clearance, and...
. In some areas they cooperate with local fishermen by driving fish toward the fishermen and eating the fish that escape the fishermen's nets.
Other interactions with humans
Cetacean bycatch
Cetacean bycatch is the incidental capture of non-target cetacean species by fisheries. Species which are seriously affected by this include dolphins, porpoises, and whales. Bycatch can be caused by entanglement in fishing nets and lines, or direct capture by hooks or in trawl nets.Cetacean bycatch...
of tuna fishing.
Conservation
The North Sea, Baltic Sea, Mediterranean and Black sea populations of the common bottlenose dolphin are listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMSBonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
), since they have an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
The species is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS
ASCOBANS
ASCOBANS is a regional agreement on the protection of small cetaceans that was concluded as the “Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas” under the auspices of the UNEP Convention on Migratory Species, or Bonn Convention, in September 1991 and came into force...
), the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS
ACCOBAMS
ACCOBAMS, the Agreement on the Conservation of Cetaceans in the Black Sea,Mediterranean Sea and contiguous Atlantic area is ‘a cooperative tool for the conservation of marine biodiversity in the Mediterranean and Black Seas’....
), the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU)and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia ( Western African Aquatic Mammals MoU).
Further reading
- Heptner, V. G.; Nasimovich, A. A; Bannikov, Andrei Grigorevich; Hoffmann, Robert S, Mammals of the Soviet Union, Volume II, part 3 (1996). Washington, D.C. : Smithsonian Institution Libraries and National Science Foundation
- Ryan, C., Rongan, E. and Cross, T. 2010. The use of Cork Harbour by bottlenose dolphins (Tursiops truncatus (Montagu, 1821)) Ir Nat. J. 31: 1 - 9.
External links
- Convention on Migratory Species page on the Common bottlenose dolphin
- Official website of the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas
- Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
- Webpage on the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia at CMS
- Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region