Ocean Sunfish Could Offer Clues to the “Rise of Slime”

A controversial hypothesis suggests that jellyfish may one day rule the oceans, and Mola mola may tell us if we are approaching a tipping point.

Written byAshley Yeager

| 4 min read

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HOLY MOLA: The ocean sunfish can grow to more than two meters in length, with a mass of up to 1,000 kilograms.© ISTOCK.COM/LEOPATRIZI

Off the coast of the French town Banyuls-sur-Mer, dozens of dorsal fins bob up and down in the water. A quick glance may suggest something menacing, but a longer look gives way to an even greater surprise: big, bizarre fish called Mola mola, from the Latin word for millstone. Commonly known as ocean sunfish, these behemoths tip the scales at up to 1,000 kilograms, making them one of the largest bony fishes alive today.

More intriguingly for the researchers who study them, some populations of ocean sunfish seem to be on the rise. “It’s quite striking in the western Mediterranean. I was there diving last spring and there were so many sunfish,” says David Grémillet, an expert on seabirds at the Center for Functional and ...

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Meet the Author

Ashley Yeager
Ashley started at The Scientist in 2018. Before joining the staff, she worked as a freelance editor and writer, a writer at the Simons Foundation, and a web producer at Science News, among other positions. She holds a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT. Ashley edits the Scientist to Watch and Profile sections of the magazine and writes news, features, and other stories for both online and print.
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