Friday Fellow: Ocean Sunfish

by Piter Kehoma Boll

Let’s swim to the world of fishes once more. And today we are meeting the heaviest of the bony ones, the ocean sunfish!


The ocean sunfish looks like a giant piece of mushroom, don’t you think? Photo by Per-Ola Norman.

Scientifically known as Mola mola, the ocean sunfish is found in tropical and temperate oceanic waters throughout the world and has a very strange look. And this is not the only strange thing about it. More than being the heaviest bony fish in the world, weighing up to 1,000 kg, it feeds almost exclusively on jellyfish, eating a huge amount of them to become that big. Also, the female ocean sunfish is known to produce up to 300 million eggs at a time, more than any other vertebrate!

The weird lump on their rear end is not a caudal fin. Actually, sunfish have no tail at all. This structure, called clavus, is formed by projections of the dorsal and anal fins.

Despite their huge size, sunfishes are not a direct threat to humans. People can swim among them without any problem. The most common forms of accidents with these fish are caused when boats collide with them or when a sunfish jumps out of the water and ends up inside a boat. Imagine a 500-kg fish landing on your head!

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McGrouther, Mark (2011).”Ocean Sunfish, Mola mola“. Australian Museum Online. Available at <;. Access on December 8, 2016.

Wikipedia. Ocean sunfish. Available at <;. Access on December 8, 2016.

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Filed under Fish, Friday Fellow, Zoology

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