Marine turtles have lived in the oceans for over 100 million years. They are an integral part of the traditional culture of many coastal indigenous peoples throughout the world.
Marine turtles migrate long distances between their feeding grounds and nesting sites. They have a large shell called a carapace, four strong, paddle-like flippers and like all reptiles, lungs for breathing air. The characteristic beak-like mouth is used to shear or crush food.
All marine turtle species are experiencing serious threats to their survival. The main threats are pollution and changes to important turtle habitats, especially coral reefs, seagrass beds, mangrove forests and nesting beaches. Other threats include accidental drowning in fishing gear, over-harvesting of turtles and eggs, and predation of eggs and hatchlings by foxes, feral pigs, dogs and goannas.
Species found in Australia
There are only a few large nesting populations of the green, hawksbill and loggerhead turtles left in the world. Australia has some of the largest marine turtle nesting areas in the Indo-Pacific region and has the only nesting populations of the flatback turtle.
Of the seven species of marine turtles in the world, six occur in Australian waters:
- Flatback turtle (Natator depressus)
- Green turtle (Chelonia mydas)
- Hawksbill turtle (Eretmochelys imbricata)
- Leatherback turtle (Dermochelys coriacea)
- Loggerhead turtle (Caretta caretta)
- Olive Ridley turtle (Lepidochelys olivacea)
The only species that does not live in Australia is the Kemps Ridley turtle.
Other interesting facts about sea turtles;
- They think jellyfish are delicious.
Leatherbacks and hawksbill turtles feed on jellyfish and keep their populations in check. Plastic looks like jellyfish when it’s floating in the water and that’s why so many turtles die from ingesting plastic—they were going for a tasty snack.
- They’re the oceans’ lawnmowers.
Green sea turtles have a more plant-based diet and eat seagrass. By keeping seagrass short, they prevent it from getting tall and harming other marine creatures.
- They cannot retract into their shell like other turtles.
Since they don’t have to protect themselves from predators for most of their life on water, sea turtles cannot retract their flippers and head into their shells. Their anatomy makes them more agile when under the sea but highly vulnerable when nesting and hatching.
- Temperature dictates the sex of baby turtles.
Warmer nests lead to more females and cooler ones lead to more males—which is why climate change could drastically affect their populations by creating too many females and too few males to match them for reproduction.
- They’ve been around for a very, very long time.
An estimated 110 million years is how long sea turtles have existed on Earth, which means they once shared the planet with T-Rex and other dinosaurs.
- They can hold their breath for five hours underwater.
To accomplish this mighty feat they slow their heart rate to up to nine minutes in between heart beats in order to conserve oxygen.
- They live to about 100 years.
And that’s also roughly the amount of eggs they lay every time they nest.
- Dogs are not a sea turtle’s best friend.
Even though they’re marine animals, some of their natural predators include dogs who dig up their eggs buried in the sand.
- They have an excellent sense of direction.
Sea turtles can detect the Earth’s magnetic field and they use it as a compass.