Flatback turtle

Natator_depressus00

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The flatback turtle is a medium sized sea turtle living around Australia and Oceania. Most animals have a reason for their name, and this one is no different. They have a much flatter shell than most sea turtles do. Although this has nothing to do with their name, they also are not as green in color as most sea turtles are. Their carapace (basically another name for their shell), can be grey, grayish-green, or olive green. Their underside is a pale yellow. They are probably the least studied and least known sea turtles along with having maybe the smallest geographic range of all of them. Until 1988, flatback turtles, were thought to be a type of green sea turtle.

Size

Adults have a shell that can be up to 3.25 feet (99 cm) in length. Because this is their shell’s length, their whole body is longer because the head is included. They can be pretty heavy for their size. The maximum weight is about 220 pounds (100 kg)

Diet

Flatback turtles are omnivores, eating both plants and animals. Some of their prey includes sea cucumbers, jellyfish, seaweed, coral, fish, mollusks, and almost all other types of oceanic invertebrates.

Habitat and range

Flatback sea turtles live mainly in waters around Oceania. More specifically they live in the northern three-quarters of Australia and the southern part of Indonesia and Papua New Guinea. They only breed and nest in Australia, though. Unlike most sea turtles, this species does not generally swim in deep waters, and they never undertake open-ocean migrations.  They are rarely found in waters deeper than 200 feet (61 m).800px-Lieux_pontes_tortue_natator_depressus

Status and threats

The IUCN does not have enough data to correctly evaluate the status of this species. It is, however, known to be threatened; the extent of these threats is not known, though. Most people think that these turtles are extremely threatened, and much should be done to protect them. Some threats include pollution, oil spills, entanglement in nets, harvesting of their eggs, and destruction of nesting sites. One of their few known natural predators is the saltwater crocodile. Flatback turtles are also common by-catch in the fishing industry. Of all turtle by-catch, flatback turtles make up 50-60%.  Because these turtles only nest in Australia, a lot of their nesting range is polluted by tourism. The Great Barrier Reef is a popular tourist destination, and this makes this area dangerous to lay eggs. People digging in the sand could accidentally unearth a flatback turtle nest. Because of how rare these turtles are thought to be, approximately 75% of their nesting habitat is protected. Another conservation act is restricting boating speeds in certain areas. This helps keep the turtles from being stressful. There are an estimated 20,000-21,000 nesting females.

Nesting

Mating season depends on the location of the nesting site. Mating and/or nesting is going on pretty much year round in different parts of Australia. In the more northern parts of Australia, mating season is in between October and January, while in the South, it is between June and August. Right before laying eggs, the females crawls out of the ocean, usually a night, and digs a hole using her hind flippers. The hole is about one foot (30 cm) deep and 9 inches (23 cm) across. During the next ten minutes, the female lays from fifty to sixty eggs. This is not a lot for sea turtles as some other species lay up to 200. The eggs are about two inches (51 mm) in length and weigh 2.7 oz. (77 g). For comparison, a medium-sized chicken egg weighs about 1.7 oz. (48 g). After laying her eggs, the female flatback sea turtle goes back into the ocean. During each nesting season, females lay two to four clutches of eggs about two weeks apart. Although they do not lay as many eggs per clutch as most sea turtles do, they lay more clutches. After laying each clutch, the female fills in the hole and forms a mound over the nest. As with many reptiles, the temperature of the nest determines the gender of the babies. Eighty-four degrees Fahrenheit (29 C) or higher produces females, and lower than that temperature makes males. Eggs can be preyed on by foxes, dogs, and pigs. On some beaches, feral pigs consume up to 90% of all flatback turtle eggs.

Young and behavior

About six to eight weeks after they are laid, the eggs hatch. At this time, the young weigh about 1.5 oz. (42 g), and their shells are just 2.4 inches (61 mm) long. Although this is not very large, this species has the largest eggs and hatchlings of all sea turtles relative to the adult body size. This is probably because the females lay fewer eggs at a time than most sea turtles do. The young’s instincts guide them to the ocean, but they do not all go in a strait line. Instead, they fan out. At this point in their life, predators include crocodiles, lizards, birds, and crabs. At seven years of age, these turtles are mature. They have a long lifespan, and can live up to 100 years.

Flatback turtles have a very laid back lifestyle, and they spend much of their day just floating at the surface of the water. It is also common to see birds resting on the backs of these turtles. When the turtles are resting, their heads are underwater, so they cannot breathe. They can hold their breath for a long time, unless they are stressed or excited.

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Sources:

Photo credits:

  • Flatback turtle – Lyndie Malan
  • Flatback turtle range – Pinpin
  • Mystery animal – Greg5030

One Response

  1. Larry Madson
    Larry Madson at |

    It is a red panda.
    Grandpa

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