Ninja Turtles are undoubtedly cool. But have you ever tried freediving with sea turtles? Here on Nusa Penida, you have every chance to try! Being an important migration route, Indonesia has six out of seven of the world’s species of sea turtles. Nusa Penida can boast of two of them nesting on its beaches and feeding on its reefs. You’re most likely to see the critically endangered Hawksbill turtles hanging around, searching for their favorite food: sponges. If you’re lucky, you’ll also notice green sea turtles in shallow waters feeding on seagrass. You can tell these species apart by their beaks and shells: green sea turtles have a round beak and a larger greenish shell with a soft round edge. Hawksbill turtles have a smaller shell with a serrated edge and dark and pale brown markings as well as a sharp pointy beak they use to reach into small holes and fissures in the reefs to find food.
If you’re respectful, beautiful sea turtles will eagerly pose for your videos and even selfies. And to appreciate these unique animals, let’s learn some interesting facts about sea turtles!
1. Sea turtles are the most ancient living reptiles
Scientists believe it was during the reign of dinosaurs (the Late Jurassic period) that turtles entered the sea. As reptiles, they require air to breathe and land to lay their eggs, but they spend most of their life underwater.
2. Unlike land turtles, they can’t retract their head and limbs into their shells
Don’t believe cartoons! Turtles can’t get out of their shells. They’re not “inside” their shells, they ARE the shells. A turtle’s shell is made of 50 bones (except leatherback turtle, which has no bony shell). Sea turtles have aerodynamic shells, flatter and smoother than those of land turtles, as they need to reduce drag and increase stability in the open ocean. This means they can’t retract their head and limbs.
3. There are only 7 species of sea turtles left
These are: flatback, green, hawksbill, loggerhead, leatherback, Kemp’s ridley, and olive ridley. The conservation status of 6 of them is endangered, critically endangered, or vulnerable. We don’t have enough data about the seventhth (flatback sea turtle) to draw an accurate conclusion on its conservation status.
4. Sea turtles can develop speed of up to 35 km/h
They’re able to migrate for thousands of kilometers between feeding and nesting areas. Usually, sea turtles cruise at around 1.5 to 9 km/h, but a startled turtle can develop speed of up to 35 km/h. Comparatively, swimmer Michael Phelps, a multiple Olympic gold winner, can only reach about 8 km/h. So don’t you ever dare to call a turtle slow! It’ll easily outswim you.
5. They can spend up to 40 min underwater
Sea turtles have lungs and breathe air, which means they need to surface from time to time to take an inhale. Thanks to slowed heart rate, increased lungs, and high oxygen diffusion capacity, an active sea turtle can spend up to 40 minutes underwater, while a sleeping one can remain underwater for up to 7 hours! But turtles can also drown: under stressful conditions, a turtle’s breathhold period decreases significantly. So if you notice a resting turtle, don’t disturb its sleep. This can literally kill it.
6. To hatch eggs, sea turtles return to the beach where they were born
This phenomenon is called natal homing. After mating in the water, female turtles crawl to the shore and dig nests for eggs with their hind flippers. A clutch may contain 50 to 350 eggs, depending on the species. After spending a couple of exhausting hours on the land, they drag their bodies back to the sea, leaving the eggs unattended.
7. Baby turtles have temperature-dependent sex determination
Unlike humans, sea turtles don’t have sex chromosomes. Their sex is determined by the temperature at which the egg incubates. Warmer temperatures produce female hatchlings, while cooler temperatures produce male ones.
8. 90% of hatchlings don’t even reach the sea
There are plenty of dangers for the eggs: nests can be ravaged by humans, birds, or crabs, or invaded by insects or fungi. Some hatchlings aren’t strong enough to leave the nest. Then, as they start crawling in the direction of the sea, they are attacked by predators. So most of the cute baby turtles never make it to the sea. Only 1% of those who did reach sexual maturity.
9. Sea turtles have an internal magnetic compass
They have magnetic crystals in their brains to detect information about the intensity of Earth’s magnetic field, which they use to navigate along with wave directions, sunlight, and temperatures. Their other most important senses are smell and vision. A sea turtle’s eyes are best adapted for diurnal activity and designed to operate underwater.
10. They can live from 50 to 100 years
It takes a sea turtle two decades to reach sexual maturity, but once it does, it has few natural enemies. The biggest threats they face are unintended capture in commercial fishing, habitat loss, pollution, and climate change.
It’s estimated that sea turtle population in Indonesia was reduced to 90% of its former level. The government recognized the urgent necessity to protect and restore the population of turtles and established a number of conservation measures. You can protect turtles, too! When you meet them, don’t touch or chase them to take pictures. Respect their personal space. Never feed them, as the food you give them might be dangerous for them. And never disturb them if they sleep. These rules are very simple, and if you follow them, you can be sure you’ve made one turtle happier!
We can guarantee you a turtle encounter during our unique freediving trips around Indonesia!
