Flatback Turtle

The flat turtle (Natator depressus), also known as the Australian flat sea turtle o flat turtle, is a species of sea turtle found in the coastal waters of Australia. Unlike other sea turtles, the flatback turtle has a flat, wide body perfectly adapted to its habitat in the shallow coastal waters of the Australian region. The species Natator is a monotypic genus of the family Cheloniidae, which includes the species Natator depressus.

Distribution

The flat turtle is an endemic species of Australia's coastal waters. It can be found in the northern part of the country, from the Great Barrier Reef in the east to the Torres Strait, in the state of Papua New Guinea e Indonesia. Another area where it is found is the Gulf of Carpentaria, the Arafura Sea, the Timor Sea, and the Indian Ocean up to northern Perth in the west.

Characteristics

We must not confuse the flat turtle (Natator depressus) with the green turtle (Chelonia mydas) due to their similar appearance.

The most distinctive feature of its shell is its great flatness, more pronounced on the third and fourth vertebrae. This is where the name flat turtle comes from.

The skin covering the shell is thin and keratinized, making it sensitive and easily damaged. It is slightly sticky to the touch and its color is generally grayish or pale greenish.

The plastron is narrower at the front and back, cream or yellow in color, as is the underside of the legs and tail.

The head is medium-sized and a slightly prominent beak. The lower jaws have serrated edges on the sides. It has a pair of elongated prefrontal scales and three large postocular scales, as well as many small scales below the eye.

The front legs are medium-sized and have a set of very fine scales, surrounded by a row of larger scales on the front of the limb, but especially on the back. The tip of the fin is particularly rounded and has only one visible claw. The legs are gray to olive on top, as are the neck and head, and lighten to cream or yellow on the sides and underside.

Habits

The flat turtle it prefers shallow, slightly murky waters rather than the waters of the Great Barrier Reef lagoons. It usually frequents bays near the coast, where it feeds on a variety of invertebrates such as sea cucumbers, jellyfish, and bivalve mollusks. It rarely ventures into deep waters, such as the Torres Strait, and is often accidentally caught by shrimp trawlers in Papua New Guinea.

How big is the flatback turtle?

Specimens of the species usually measure around 1 m and weigh 70 kg. But in the case of females, there are flatback turtles that reach 135 cm in size y 150 kg in weight.

What does a flatback turtle eat?

This species of sea turtle primarily feeds on algae and small invertebrates found in coastal waters. Unlike other sea turtles that mainly feed on live prey, the Natator depressus feeds opportunistically and consumes fish scraps and other waste. Other foods it eats include seaweed, shrimp, and crabs.

Reproduction

The nesting period mainly occurs in November and December, although it can happen throughout the year. Females dig their nests in the sand early in the morning or at dusk, at the base of the dunes.

Several clutches are laid per season, with a maximum of four, and about 15 days between each clutch. Each clutch contains between 50 and 65 eggs, although sometimes up to 70 can be found.

The eggs are large (5 cm in diameter), with a parchment-like shell and white color. The incubation period is relatively short, from 42 to 50 days. The hatchlings emerge from the sand after a significant drop in temperature and as night falls.

This species' strategy is to produce fewer but larger eggs to increase the juveniles' chances of survival against predators like ghost crabs.

The juveniles are larger than those of Chelonia mydas and seem to be less vulnerable to predators when both species emerge on the beaches.

Conservation Status

Juveniles of this species face predators such as osprey, monitor lizards, seagulls, octopuses, and some carnivorous fish.

It is considered the least exploited sea turtle by humans, as its meat is less appreciated in flavor than that of green turtles.

Currently, flatback turtles it is protected by laws (except for Aboriginal populations who have the right to fish and consume it). In some areas of Australia, this species has been studied and protected for many years. Due to its coastal habitat, it is especially vulnerable to pollution and human activities, and cases of diseases such as fibropapillomas have been recorded in some specimens, indicating an imbalance in water quality in certain areas. The species is listed in Appendix I of CITES.

Other Sea Turtle Species

Apart from the Australian flatback turtle (Natator depressus), there are six other species of sea turtles: the green turtle (Chelonia mydas), the hawksbill turtle (Eretmochelys imbricata), the loggerhead turtle (Caretta caretta), the leatherback turtle (Dermochelys coriacea), the Kemp's ridley turtle (Lepidochelys kempii), and the olive ridley turtle (Lepidochelys olivacea). Each has unique physical and behavioral characteristics and different distribution areas in the world's oceans. All sea turtle species are endangered due to bycatch, ocean pollution, and habitat loss.

The flat turtle (Natator depressus) is a unique species among turtles that plays an important role in the coastal waters ecosystem of Australia. Despite the challenges it faces, conservation efforts and public awareness about its importance are yielding positive results to protect this endangered species. With continued help and cooperation from everyone, we can ensure that the Natator depressus and other species of sea turtles continue to be an integral part of the Australian marine ecosystem in the future.