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Today on Animal Fact Files we’re talking about ocean sunfish. Also known as molas, these are some of the largest bony fish living in our world’s oceans. The largest species, Mola mola, is considered the largest living bony fish on our planet. If you’re thinking there’s no way they can be bigger than a whale shark, remember sharks, whale sharks included, have cartilaginous skeletons, so they don’t count as bony fish! Ocean sunfish can reach 10 feet (3 meters) in length, 13 feet (4 meters) in height and weigh up to two tons! That’s about the weight of an SUV - or a giraffe. However, not all ocean sunfish reach these gargantuan sizes; for example, the slender sunfish isn’t known to attain lengths of over 3.3 feet (100 centimeters). There are currently five described species of ocean sunfish, though it should be noted that the most recent species, the hoodwinker, was described only two years ago as of this recording, so the species number could change with more information.

Ocean sunfish are also known as “swimming heads”. It’s an apt nickname because these fish look as if their rear half was cut from their bodies leaving just a head swimming through the water. These goofy-looking fishbois are found in all temperate and tropical oceans around the world, though it’s believed they migrate towards cooler waters in the spring and summer to follow their prey of zooplankton. Ocean sunfish also eat algae, small fish, squid, crustaceans, brittle stars, and jellyfish. They especially love jellyfish! Ocean sunfish have a beaklike mouth and they don’t chew their food. Instead they’ll push their food back and forth through their beaks to break up their prey and then swallow the smaller pieces whole. Plastic bags floating in the water that can be mistaken for jellyfish are a threat to ocean sunfish. Accidental ingestion of this plastic waste can lead to suffocation or starvation. Think of the ocean sunfish and try to use reusable bags whenever you can!

Ocean sunfish might look like they would be poor swimmers with their floppy little fins, but they can get around. Remember, they freaking migrate! Actually, they might migrate vertically throughout the day, too, like a nautilus. Ocean sunfish are generally known as surface dwelling animals but they dive deep to search for prey during the day. They may also dive to escape predators which can include killer whales, sharks, and sea lions. After these deep dives, ocean sunfish return to the surface to warm up in the warm rays of the sun. They can even breach themselves like a great white shark, jumping out of the ocean and slamming their bodies back onto the waves. They do this to dislodge parasites from their skin.

Ocean sunfish are often hosts to many parasites - so many that even their parasites can have parasites. While they swim on the water’s surface, ocean sunfish may even allow birds to pull parasites from their skin. They’ll also enter reef environments and give other fish a chance at the buffet living on their skin. Fish like wrasses and angelfish will happily eat the parasites from the ocean sunfishes' skin. This tends to be why ocean sunfish are seen in reefs, otherwise they’re found in the open ocean. It’s likely ocean sunfish have so many parasites because they’re relatively slow moving animals, though they are able to reach speeds of… 2 miles per hour (3.2 km/hr). To be fair, I don’t think Chester could run two miles in an hour unless there was a large plate of food at the finish line, so they’d have him beat.

Little is known about ocean sunfish mating, but it is currently thought that they are closely related to pufferfish. Like pufferfish, the larvae of ocean sunfish look like little spikey balls. As they grow, they develop into the swimming head shape and lose their spikes. Their tails, which are obviously a bit different from other fish tails, are hard rods that act like rudders. Supposedly these gentle giants can live to be more than 100 years old according to Animal Diversity Web, but there is still a lot more research that needs to be done before we can be sure!

For more facts on ocean sunfish, check out the links in the description. Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.