Tursiops truncatus gillii

Tursiops truncatus gillii

Common bottlenose dolphin, Atlantic bottlenose dolphin

Kingdom
Phylum
Subphylum
Class
Order
Infraorder
Family
Genus
SPECIES
Tursiops truncatus gillii
Life Span
17 years

The common bottlenose dolphin or Atlantic bottlenose dolphin (Tursiops truncatus ) is a wide-ranging marine mammal of the family Delphinidae. The common bottlenose dolphin is a very familiar dolphin species due to the wide exposure it receives in captivity in marine parks and dolphinaria, and in movies and television programs. It is the largest species of the beaked dolphins. It inhabits temperate and tropical oceans throughout the world, and is absent only from polar waters. While formerly known simply as the bottlenose dolphin, this term is now applied to the genus Tursiops as a whole. These dolphins inhabit warm and temperate seas worldwide. As considerable genetic variation has been described among members of this species, even between neighboring populations, many experts consider that additional species may be recognized.

Appearance

Common bottlenose dolphins are grey in color and range between 2 and 4 m (6.6 and 13.1 ft) long, and weigh between 150 and 650 kg (330 and 1,430 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 ranging between 200 and 500 kg (440 and 1,100 lb). Dolphins have a short and well-defined snout that looks like an old-fashioned gin bottle, which is the source for their common name.

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Like all whales and dolphins, though, the snout is not a functional nose; the nose has instead evolved into the blowhole on the top of their heads. Their necks are more flexible than other dolphins' due to five of their seven vertebrae not being fused together as is seen in other dolphin species.

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Distribution

Geography

The common bottlenose dolphin can be found in temperate, subtropical, and tropical oceans around the world. The global population has been estimated at 600,000. Some bottlenose populations 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 populations can migrate up to 4,200 km (2,600 mi) in a season, but inshore populations tend to move less. However, some inshore populations make long migrations in response to El Niño events. The species has occurred as far as 50° north in eastern Pacific waters, possibly as a result of warm water events. The coastal dolphins appear to adapt to warm, shallow waters. It has a smaller body and larger flippers, for maneuverability and heat dispersal. They can be found in harbors, bays, lagoons and estuaries. Offshore dolphins, however, are adapted to cooler, deeper waters. Certain qualities in their blood suggest they are more suited to deep diving. Their considerably larger body protects them against predators and helps them retain heat.

Habits and Lifestyle

As a very social species, the common bottlenose dolphin lives in groups called pods that typically number about 15 individuals, but group size varies from pairs of dolphins to over 100 or even occasionally over 1,000 animals for short periods of time. The types of groups include: nursery groups, juvenile groups, and groups of adult males.

Diet and Nutrition

Its diet consists mainly of eels, squid, shrimp and a wide variety of fishes. It does not chew its food, instead swallowing it whole. Dolphin pods often work as a team to harvest schools of fish, though they also hunt individually. Dolphins search for prey primarily using echolocation, which is a form of sonar.

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The diet of common bottlenose dolphin pods varies depending on area. Along the U.S. Atlantic coast, the main prey includes Atlantic croakers (Micropogonias undulatus ), spot (Leiostomus xanthurus ) and American silver perch (Bairdiella chrysoura ), while in South Africa, African massbankers (Trachurus delagoa ), olive grunters (Pomadasys olivaceus ), and pandora (Pagellus bellottii ) are common bottlenose dolphin's typical prey.

According to combined stomach content and stable isotope analyses in the Gulf of Cádiz, although European conger (Conger conger ) and European hake (Merluccius merluccius ) are most important prey of common bottlenose dolphins, mass-balance isotopic mixing model (MixSIAR), using δ13C and δ15N showns that Sparidae species; seabreams (Diplodus annularis and D. bellottii ), rubberlip grunt (Plectorhinchus mediterraneus ), and common pandora, (Pagellus erythrinus )) and a mixture of other species including European hake, mackerels (Scomber colias, S. japonicus and S. scombrus ), European conger, red bandfish (Cepola macrophthalma ) and European pilchard (Sardina pilchardus ) are the assimilated diet.

Research indicates that the type and range of fish in a dolphin's diet can have a significant impact on its health and metabolism.

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Mating Habits

Mating behavior of bottlenose dolphin is polygamous. Although they can breed throughout the year, it mostly occurs in spring. Males form alliances to seek an estrous female. For a chance to mate with the female, males separate the female from her home range. Females bear a calf every three to six years. After a year-long gestation period, females bear a single calf. Newborn calves are between 0.8 and 1.4 m (2 ft 7 in and 4 ft 7 in) long and weigh between 15 and 30 kg (33 and 66 lb). They can live as long as 40–50 years. The calf suckling lasts between 18 and 20 months. Sexual maturity varies by population, and ranges from 5–14 years of age; sexual maturity occurs between 8 and 13 years for males and 5 to 10 years for females.

Population

Conservation

The North Sea, Baltic, Mediterranean and Black Sea populations of the common bottlenose dolphin are listed in Appendix II to the Convention on the Conservation of Migratory Species of Wild Animals (CMS) of the Bonn Convention, since they have an unfavorable conservation status or would benefit significantly from international cooperation organized by tailored agreements.

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Estimated population of a few specific areas are including:

The species is covered by the Agreement on 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, and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia.

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Coloring Pages

References

1. Tursiops truncatus gillii Wikipedia article - https://en.wikipedia.org/wiki/Tursiops_truncatus_gillii

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