Remora fish (Echeneidae) are also known as “sucker fish.” Their first dorsal fin, located on their back, works as a sucker which they use to attach themselves to large marine animals like turtles, sharks, rays and whales.
It is often thought that remora fish perform the cleaning of the larger animals because they feed off the dead skin flakes and ectoparasites they remove from these host. This is not the case. Their diet is made up primarily of feces from the host.
Some remoras attach themselves to gain the protection of their host, and, though they can swim independently, they benefit greatly from the water that flows across their gills as the host swims.
It is not unusual for remoras to attempt to attach themselves to scuba divers when in need of a new host. However, the strangest interaction between remoras and humans we have learned of is fishermen who use them as bait, reeling them in once they have attached themselves to a fish. We encountered these remora fish attached to a whale shark during a day of diving in Nosy Be, Madagascar. Read more in our post, Whale Shark Sightings and Turquoise Waters: Scuba Diving Nosy Be, Madagascar.