World Turtle Day: 10 cool facts about turtles

There's a reason why turtles look a little prehistoric. The first ever specimens evolved around 260 million years ago in the late-Triassic period. Shortly after their arrival, the Earth experienced a mass extinction event that wiped out about 90% of all life on land. Luckily for the turtles, their burrowing and water-dwelling habits set them up for long-term survival in this strange new world.

While a turtle's lifespan largely depends on the species, almost all of them have the potential to live to a ripe old age. A typical pet turtle can make it to anywhere between 10 and 80 years, while larger species often keep going for more than 100 years. Because it's so difficult to accurately measure age over a century, researchers think some turtles could even be hundreds of years old.

There are currently 356 known species of turtles. As a rule, they are all reptiles with a hard cartilage shell. But that's about where the similarities end. There are sea turtles, leatherback turtles, snapping turtles, pond turtles, soft-shelled turtles (pictured)– and of course, tortoises…

Yes, technically all tortoises are in fact turtles. They belong to the Testudines family which includes reptiles whose bodies are protected by a bony outer shell. But the main difference between turtles and tortoises is that tortoises live exclusively on land, while most turtles live in or near water.

Most turtles are actually omnivores, but a few species are more picky when it comes to their diet. Most tortoises are happy to munch on leafy greens or fruit. Not so the fearsome-looking alligator turtle, which is almost entirely carnivorous and feeds on anything from fish to small mammals that venture too close to the water's edge…

When they're ready to lay their eggs, even water-dwelling turtles will dig their nests in the sand or the earth near their habitat. But they're not the nurturing type. No species of turtle sticks around to raise their young. When the babies hatch, they're on their own.

Like crocodiles and alligators, a turtle's gender is determined after fertilization. If a turtle's eggs incubate below 27.7 degrees Celsius, the hatchlings will be male. But if the eggs incubate above 31 degrees, they will be female. If the temperature is somewhere in-between, or fluctuates, a mix of male and female babies will hatch. As oceans warm, turtles tend to give birth to more females.

Sea turtles are known for their amazing ability to return to the exact beach where they were born years later. Like many animals, turtles can navigate their way at sea by sensing the individual lines of the magnetic field. But they can also remember the magnetic signature of coastlines and sense tiny variations in magnetic fields, allowing them to guide themselves home.

Turtles have strong underwater eyesight. Researchers have discovered that they can see a range of different colors – and even prefer some colors to others. Although sea turtles are famous for their internal GPS, there is evidence to suggest they do not see very well on land.

Having survived for millions of years, six out of seven turtle species are classified as threatened or endangered as a result of human activity. Every year, thousands become trapped in commercial trawl nets, while in some parts of the world they are killed for their eggs, meat and shells.