By Stacey Venzel
A number of turtles have specialized digestive tracts that allow them to consume toxic or potentially harmful creatures. One turtle probably surprises us all with the ability to man-handle slippery blobs of jellyfish in its throat, all without being bothered by the stinging!
Anatomy of a turtle is important in determining its preferential diet. Not only has the leatherback adapted to eat jellyfish—and lots of it—but other turtles go the distance with their food sources, even as far as munching on glass.
THE JELLYFISH EATER
Inside the gigantic throat of the enormous leatherback sea turtle are 3-inch spines pointing backward to prevent jellyfish from popping out as excess water is expelled. These spines inside the elongated, winding esophagus also protect the leatherback from jellyfish stings. A razored cusp on a leatherback’s mouth helps it grab its prey and shred jellies, too.
ARE JELLYFISH ENOUGH?
Leatherback turtles take the trophy for largest turtle on the planet, and it is quite a feat when a turtle that weighs anywhere from 1,000 to 2,000 pounds can survive on the limited nutrients provided by jellyfish. However, leatherbacks are smart eaters, hunting in specific locations where jellyfish are abundant. This means they can eat a lot of jellyfish in a short amount of time, though their requirement to consume 73 percent of their body mass means they must swallow hundreds to a 1,000 pounds of jellyfish each day! But leatherbacks are not always going after small jellies, showing preference for the world’s largest jellyfish, the lion’s mane, which can measure 7.5 feet wide and 250 feet in tentacle length!
OTHER JELLYFISH EATERS
Leatherbacks are not the only ones that enjoy jellyfish. While they are the only turtles to survive solely on these gelatinous creatures, other sea turtles have the spiny throat adaptation and will take advantage of an easy meal. Loggerheads, Pacific-dwelling greens, hawksbills, Kemp’s ridleys and olive ridleys eat jellyfish every now and then.
If you thought eating jellyfish was impressive, how about a turtle that eats glass! The sponge organisms of the hawksbill sea turtle diet are made of up silica, the basic component of glass.
W Don Bowen, Susan G Heaslip, Sara J Iverson, Et. Al., “Jellyfish support high energy intake of leatherback sea turtles (Dermochelys coriacea): Video evidence from animal-borne cameras,” PLOS One, March 16, 2012, http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0033259.
Karen Eckert, David Gulko, Sea Turtles: An Ecological Guide (Honolulu, Mutual Publishing, 2004), 26, 28, 31, 32, 34-35, 41, 43.