Most turtles visiting UK waters are out of their comfort zone temperature-wise, as they’re reptiles, most of which take on the temperature of their surroundings rather than using energy to generate their own body heat. The leatherback turtle (Dermochelys coriacea), however, as well as being the world’s largest turtle (average 2.5m long; 250-700kg) is capable of maintaining a body temperature higher than that of its surroundings. They use a counter-current exchange system to do this as well as having a large amount of oils in their body. This opens up more areas of sea with plenty more jellies and jelly-type organisms to hunt and means they’re the most widely distributed of the marine turtles. Another major difference they exhibit to other marine turtles can be seen in their name – Leatherbacks. Well named – they are covered in a leathery skin, instead of a hardened shell.
they’re a fundamental link in marine ecosystems and turtles and their ancestors have been doing this for over 100 million yrs
Leatherbacks are also capable of heading down into the depths to hunt deep sea jellies too and can dive well over 1km. For this they have developed adaptations to help the dive, but the dive itself might also be an adaptation to help cope with very warm temperatures in tropical waters. They use the downwards-facing spines, which line their throat to keep hold of their prey once encountered. Like many turtles, they do a good job of keeping down jelly numbers, so they’re a fundamental link in marine ecosystems and turtles and their ancestors have been doing this for over 100 million yrs.
Tragically, leatherback populations have undergone major historic and ongoing declines. Their biology doesn’t help them recover quickly from loss; females only reaching maturity at 25-30yrs of age. Avoiding multiple threats, they can live on average to 45-50 years, but are capable of living a lot longer. A breeding female will return to land (every 2-3 yrs) to lay her own eggs, repeatedly dragging her enormous weight up steep sandy beaches, night after night.