by Stephen R. Swinburne - Lifelong Naturalist
What animal can happily and safely slurp down a lion’s mane jellyfish as if it were a big bowl of Jello™? The leatherback sea turtle!
Adult leatherbacks are the largest reptiles on earth today, averaging seven feet long. As the planet’s biggest turtle, they range from the Arctic Circle south to Antarctica, and they swim, on average, more than 6,000 miles each year. And they love lion’s mane jellyfish. As a matter of fact, lion’s mane jellyfish make up almost their entire diet. How can a seven-foot long sea turtle consume a creature armored with a hundred feet of stinging tentacles?
Often referred to as Earth’s last dinosaur, leatherback sea turtles have lived on the planet for millions of years, surviving ice ages and major extinctions. For an animal to live that long on a diet of giant blobs of gelatinous saltwater, it better be very very good at tackling and consuming its delicious but dangerous meals of giant stinging jellyfish. And, it better have developed some cool adaptations over the ages. Here’s how they do it .
First off, a sharp pointed lip acts like a hook so the turtle can snag the jellyfish and hang onto it.
Second, the turtle’s mouthful of backward-pointing spines prevents the jellyfish from escaping. A scientist once said to me, while looking into the mouth of a leatherback, “It’s the last thing a jellyfish will ever see!”
Once the leatherback has consumed dozens and dozens of jellyfish, there’s the problem of all that salt in its diet. Eating too much salt will cause dehydration. No problem for the leatherback! The turtle is perfectly adapted to rid its body of all that excess salt. Salt or lacrimal glands, located near their eyes, allow leatherbacks to secret saline tears—and then they cry them away.
So the largest marine reptile on earth evolved by getting better and better at eating the most unlikely diet, the largest jellyfish on earth.
Steve Swinburne has written a book on sea turtles. To see information about the book as well as a study guide and video and picture gallery, click here.