Stephen R. Swinburne
Lion’s mane jellyfish can grow seven feet wide with tentacles reaching a length of 100 feet. That’s the same length as a blue whale! Their bodies are 98 percent seawater. They live in the cold, boreal waters of the Arctic, northern Atlantic and northern Pacific Oceans. Slowly pulsating ocean currents carry the big jellies great distances. The long trailing, stinging tentacles capture and tear apart their prey. Swimmers beware when currents sweep lion’s manes close to shore. Their stings cause red swollen welts, and severe body contact with a lion’s mane jellyfish may be deadly.
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.
Steve Swinburne is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.
MLA 8 Citation
Swinburne, Stephen R. "Who Eats the Largest Jellyfish in the World -- and Enjoys It?" Nonfiction, iNK Think Tank, 12 Oct. 2017, www.nonfictionminute.org/the-nonfiction-minute/who-eats-the-largest-jellyfish-in-the-world-and-enjoys-it.
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