Transcript:

Today on Animal Fact Files we’re discussing remoras. These fish are also known as sharksuckers and suckerfish. Many people erroneously believe that these fish use their mouths to suction themselves to other animals, much in the same way a pleco may suction itself to the side of an aquarium tank, but remoras don’t use their mouths to attach to their hosts - it gets a little weirder than that.

The name remora means something along the lines of “hindrance” because they were believed to cause just that. These fish don’t just cling to animals, they’ll also cling to boats, and ancient mariners thought the fish slowed their ships down! In fact, many remoras connected to an individual host are known to cause drag on that host making the animal slower in the water, though generally remoras are not considered harmful to a host. At most, the fish are believed to be an irritation to host animals and may even tickle the animals they attach to!

Remoras cling to other animals in order to gather food. They don’t have a swim bladder, so they aren’t the strongest swimmers. Attaching to a host also helps them move around and may provide them protection from predators. Some animals are known to try and remove remoras like dolphins who will pluck the clinging fish off themselves and their babies. Remora hosts don’t eat remoras, though - for example we weren’t able to find any documentation of remora remains inside a shark’s stomach; so the hosts don’t really seem to bother the remoras either! While clinging to a host, remoras gather food scraps and they’ll eat parasitic crustaceans like copepods from the host's skin, so they can even be beneficial!

While remoras are able to swim freely, they’re generally associated with their clinging behavior. Remoras cling to sharks as well as manta rays, whales, dolphins, sea turtles, dugongs, and more. It might look like these fish are pressing their mouths against the host’s body in a dramatic clingy kiss, however it’s the top of a remora’s head that attaches to a host - not the mouth. Using a modified dorsal fin - which is the back fin that most people associate with sharks and dolphins that sticks up out of the water - a remora attaches itself to its host. Their dorsal fin develops into plates with spaces between them. The remora raises the plates and the space between creates suction. This suction is so strong remoras are used for fishing. Anglers will tie a string to the remora’s tail and, once the fish has located a host and grabbed a hold, the angler will pull the remora attached to the host up until the angler is able to catch the host: the actual target of their angling!

In size, remoras average 15 inches (40cm) in length but can more than double that in larger species! They’re found worldwide in warm marine waters. How they reproduce is understudied but they’re believed to engage in broadcast spawning where males and females release their gametes, or sperm and eggs, into the water column at the same time. The eggs harden after fertilization and are believed to be able to withstand washing up on shore due to their hard exterior. It’s unknown how long remoras live in the wild.

For more facts on remoras, check out the links in the description. Thank you to bibarel for today’s request! Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files!