- Flatback Turtle
name = Flatback Turtle
status = DD
status_system = iucn2.3
phylum = Chordata
genus = "Natator"
genus_authority = McCulloch, 1908
species = "N. depressus"
binomial = " Natator depressus"
binomial_authority = (Garman, 1880)
The Flatback Sea Turtle (or simply Flatback), "Natator depressus", is a
sea turtlethat is endemic to the continental shelfof Australia.
Ecology and life history
Flatback turtles are usually found in bays, shallow, grassy waters, coral reefs, estuaries and lagoons on the northern coast of Australia and off the coast of
Papua New Guinea.
The Flatback Turtle is known to be rather broad in its eating habits and can eat a variety such as seagrass, marine invertebrates (such as mollusks, jellyfish and shrimp) and fish. It also is known to be a consumer of soft coral, sea cucumbers and other soft-bodied creatures.
The Flatback turtle is unusual because it lays fewer, but larger eggs than the other
sea turtlespecies. Females emerge onto the beach on which they hatched more than 30 years ago and make their way up the beach to lay their eggs. (Male turtles never return to the shore, as mating occurs at sea.) This takes around an hour and a half. The female digs a pit using her front flippers to clear away the topmost layer of dry sand,. She then uses her rear flippers to dig a small egg chamber. After laying between 50 and 75 eggs she covers them first with her hind flippers, and then flings sand back with her front flippers. Females will lay a clutch of eggs around every 16-17 days during the nesting season, with between one and four nests being laid in total. They will only nest every 2-3 years. There are around 54 eggs in each clutch, and the rookeriesare usually small.
These eggs are vulnerable to predation by
dingoes, sand goannas ("Varanus gouldii") and the introduced pest species - the fox. An altered ecology at known nesting sites, such as Port Hedland, have resulted in disturbances to the breeding behaviour of the turtle. Adult specimens are also found in the nets of fishing trawlers, and are still consumed by the indigenous peoples of its distribution range.
Hatching is the most dangerous time for flatback. Guided by the low, open horizon, the newborns make a dash for the sea. Only safety in numbers will protect them from birds and crabs. However, even the sea is not safe. Sharks and fish patrol shallow waters, waiting to prey upon the hatchlings. Scientists estimate only 1 out of 100 turtles live to become an adult.Fact|date=June 2008 However, as these turtles become adults there are very few organisms that
predatethem. The survivorship curveis known as a Type III because there is high mortality for these animals as hatchlings but there is a very low mortality rate as they become older.
carapaceof the adult is on average 90 cmlong. This is low domed, the edge is upturned and has four pairs of costal scales–fewer than other marine turtles of the region. An olive-grey colour is found on the upper parts, and it is more pale ventrally. A single pair of scales are located at the front of the head, which also distinguish this species.cite book |last=Burbidge |first=Andrew A |authorlink= |coauthors= |editor= |others= |title=Threatened animals of Western Australia |origdate= |origyear=2004 |origmonth= |url= |format= |accessdate= |accessyear= |accessmonth= |edition= |series= |date= |year= |month= |publisher=Department of Conservation and Land Management |location= |language= |isbn=0 7307 5549 5 |oclc= |doi= |id= |pages=110, 114 |chapter= |chapterurl= |quote=]
Flatback turtles are found in coastal waters. The species may feed in the waters off
Indonesiaand Papua New Guinea, but it nests only in Australia. Nesting occurs across the top half of Australia, from Exmouth in Western Australia to Mon Reposin Queensland. The most significant breeding site is Crab Island in the western Torres Strait. Breeding may also occur on the islands of the southern Great Barrier Reef, and on mainland beaches and offshore islands north of Gladstone.
Naming and taxonomic history
This species is contained by a
monotypicgenus, "Natator", that is found in the Cheloniidaefamily. "depressus", the species indicator (the second part of the scientific name means "flat" in Latin. This refers to the flatness of the Flatback's shell. The Bardi peoplecalled this animal barwanjan, and it was known to the Wunambilas madumal.
The species is considered vulnerable to extinction in
Western Australia, but the Red listof the IUCNnotes that is data deficient and unable to be correctly assessed. [IUCN2006|assessors=Red List Standards & Petitions Subcommittee|year=1996|id=14363|title=Natator depressus|downloaded=12 May 2006 Database entry includes a lengthy justification of why this species is listed as data deficient] , it is likely that these turtles will become extinct in the foreseeable future. If this species disappears, the ecosystems it is a part of will surely crumble.Fact|date=June 2008 The seagrasses these turtles feed on are breeding grounds for certain organisms that can only survive if the grass is kept short, much like the grass in our front yard.Fact|date=June 2008 The organisms that thrive in the seagrass would die out, causing a chain reaction of the organisms that feed off them to die out, and so on.Fact|date=June 2008
Chelonioidea". The sea turtlesuperfamily.
* [http://www.gbrmpa.gov.au/corp_site/key_issues/conservation/threatened_species/turtles/flatback_turtles.html Great Barrier Reef Marine Park Authority: Flatback Turtles]
* [http://www.iucnredlist.org/search/details.php?species=14363 IUCN Red List of Threatened Species: Flatback Turtle]
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Look at other dictionaries:
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