How Remoras Benefit from Riding Sharks and Whales

Remoras, commonly known as suckerfish, are famous for their clingy behavior. As their name suggests, they often suction themselves onto specific large marine animals such as sharks, rays, whales, and sea turtles. By hitching rides on larger animals, remoras save energy in ways other fish cannot, making them seem especially clever. This YouTube Short posted by @Animal.LifeCBP shows a remora in action. Read below to learn more about why these animals are so clingy.

About Remoras

Remoras get their nickname, “suckerfish,” for a very obvious reason. These ray-finned fish are flat, with a distinct oval suction disc on the top of their heads. This suction disc, which evolved from a modified dorsal fin, allows the fish to attach itself to large sea animals. While this may seem like a parasitic relationship, the suction cup typically causes little to no harm to the host, though minor skin irritation or abrasions can occasionally occur. Instead of constantly swimming and exhausting themselves in the open ocean, remoras can conserve energy by riding on their hosts. They inhabit warm ocean waters throughout the world, and where you find them depends on where their host is traveling. Some places where they are more commonly seen include coral reefs and shipwrecks, as their hosts are likely to travel through these areas as well.

If remoras spend so much time attached to their hosts, how do they get food? To conserve energy, they rely on their hosts for food in subtle ways. One way is by feeding on the scraps of the host’s meals. Sharks, a common host, are not the cleanest eaters, and often leave scraps of their meals floating around. Remoras take advantage of these leftovers as a convenient food source. They also eat dead skin and parasites from their host’s body, which benefits the host by keeping it cleaner. Remoras are opportunistic feeders, and their long-standing dependence on hosts has shaped their evolution.

Suckerfish Hosts

Another nickname for the remora is ‘sharksucker,’ as sharks are a common host. Sharks are not only quick in the water, but are also constantly hunting and leaving messes in their wake. This mess provides a free meal for the remora, while the shark also transports them through the ocean. This makes sharks an extremely common host and is the reason for one of the remora’s nicknames. Other common hosts include rays, whales, dolphins, sea turtles, and sometimes, boats. Each of these animals provides the transportation remoras need, though not all offer the same amount of food. Because remoras help remove dead skin and parasites, most hosts, including sharks, tolerate their presence. Sharks often ignore remoras entirely, suggesting an almost mutualistic relationship.