Flatback sea turtle
The Australian flatback sea turtle (Natator depressus)[4] is a species of sea turtle in the family Cheloniidae. The species is endemic to the sandy beaches and shallow coastal waters of the Australian continental shelf. This turtle gets its common name from the fact that its shell has a flattened or lower dome than the other sea turtles. It can be olive green to grey with a cream underside. It averages from 76 to 96 cm (30 to 38 inches) in carapace length and can weigh from 70 to 90 kg (154 to 198 lb). The hatchlings, when emerging from nests, are larger than other sea turtle hatchlings when they hatch.
The flatback turtle is listed by the IUCN Red List of Threatened Species as data deficient, meaning there is insufficient scientific information to determine its conservation status at this time.[1] It was previously listed as vulnerable in 1994.[5] It is not as threatened as other sea turtles due to its small dispersal range.[6] This animal can be 31 to 37 inches long and about 100 kg in weight
Taxonomy[edit]
The flatback sea turtle was originally described as Chelonia depressa in 1880 by American herpetologist Samuel Garman. The genus Natator (meaning "swimmer") was created in 1908 by Australian ichthyologist Allan Riverstone McCulloch, and in the same scientific paper he described what he thought to be a new species, Natator tessellatus, thereby creating a junior synonym. In 1988 Swiss paleontologist Rainer Zangerl assigned the flatback sea turtle to the genus Natator as the new combination Natator depressus. Because Chelonia is feminine, and Natator is masculine, the specific name was changed from depressa to depressus.
Distribution and habitat[edit]
The flatback sea turtle has the smallest range of the seven sea turtles. It is found in the continental shelf and coastal waters of tropic regions. It does not travel long distances in the open ocean for migrations like other sea turtles. It can typically be found in waters of 60 m (200 ft) or less in depth.[10] It does not have a global distribution like the other sea turtles. The flatback sea turtle can be found along the coastal waters of Northern Australia, the Tropic of Capricorn, and the coastal areas of Papua New Guinea. Its distribution within Australia is in the areas of eastern Queensland, Torres Strait and Gulf of Carpentaria, Northern Territory, and Western Australia.[11]
The distribution of nesting sites can be found across Queensland, the Northern Territory, and Western Australia, with the greatest concentration found in Queensland, in the Gulf of Carpentaria.[10] Within Queensland, the nesting sites can be found from the south in Bundaberg to the Torres Strait in the north.[11] The main nesting sites in this range are the southern Great Barrier Reef, Wild Duck, and Curtis Island.[11] The Torres Strait contains the major nesting sites for these turtles. Within the Northern Territory, nesting sites are more widely dispersed in this area with a wide variety of beach types on this coastline.[11] In the Western Australia area, the important nesting sites found have been the Kimberley Region, Cape Dommett, and the Lacrosse Island.[11]
The flatback sea turtle lives in the shallow, soft-bottomed tropical and subtropical waters. This turtle sticks to the continental shelf of Australia and can be found in grassy areas, bays, lagoons, estuaries, and any place with a soft-bottomed sea bed.[5][12] The habitats that females prefer for nesting sites are sandy beaches in tropical and subtropical areas.[11] They prefer beaches where the sand temperature can be in the range of 29 °C to 33 °C (84 to 91 °F) at nest depth, which are the temperatures that help determine the hatchling's sex.[11]
Life history[edit]
Early life[edit]
The hatchlings begin to leave the nests during the beginning of December, and the clutches will continue to hatch until late March.[13] The peak of hatchling emergence can be seen during February.[13] A flatback sea turtle hatchling is larger than other sea turtle hatchlings with its carapace length averaging 60 mm (2.4 in).[6] Its large size helps protect it from some of the predators after hatching, and allows it to also be a stronger swimmer.[6] The hatchlings tend to stay close to shore and lack the pelagic phase of other sea turtles.[6][11] The hatchlings will feed on the macroplankton present in their surface-dwelling environment.