The remora fish is a species found throughout the world’s tropical and subtropical oceans. This marine animal is recognized for its unique habit of attaching itself to larger marine life, such as sharks, whales, and sea turtles. The remora utilizes a modified dorsal fin on the top of its head to secure a free ride and access to food sources. This attachment behavior is central to the remora’s feeding strategy, allowing it to conserve energy. The remora’s diet is a direct consequence of this association, ranging from discarded scraps of prey to the parasites living on its host’s skin.
The Primary Diet: Scraps, Parasites, and Detritus
The majority of a remora’s nutrition is acquired directly from its close association with a host animal. This relationship is often considered commensal, as the remora gains food and transportation without harming its host. A significant portion of this diet consists of ectoparasites, such as copepods, which the remora actively grazes from the host’s skin, gills, and mouth.
The remora also consumes detritus and biological material shed by the host, including loose skin flakes, mucus, and other organic matter. When the host makes a kill, the remora will temporarily detach to consume small fragments of prey that drift away from the main carcass. This opportunistic scavenging ensures a steady food supply tied to the feeding efficiency of the larger animal it accompanies. The consumption of host fecal matter has also been documented as a food source, demonstrating the remora’s highly generalized diet when attached.
Independent Feeding and Temporary Foraging
While the remora is famous for its hitchhiking lifestyle, it is fully capable of detaching and foraging independently. This occurs especially when a host is not available or when food resources are plentiful in the water column. During these periods of free-swimming, the remora preys on smaller organisms it encounters.
The diet of an unattached remora includes small crustaceans and planktonic organisms, which it hunts in the open ocean. Independent foraging may also include small fish and larval squid, particularly for larger remora species. The ability to forage on its own prevents the remora from being entirely dependent on its host’s feeding schedule, allowing them to adapt to different ocean environments.
The Mechanism of Meal Acquisition
The remora’s feeding strategy is dependent on its unique anatomy, specifically the oval-shaped suction disc on the top of its head. This disc is composed of transverse, plate-like structures called lamellae, which can be raised and lowered to create a powerful vacuum against a host’s surface. The lamellae are supported by spinule-covered tissue that creates friction, ensuring a strong grip even against the rough texture of sharkskin or the smooth surface of a whale.
This adhesion mechanism allows the remora to move around on the host’s body to access different food sources, such as concentrated patches of parasites or debris behind fins and in gill areas. The choice of host—large, mobile animals like sharks, whales, or sea turtles—is a deliberate feeding strategy. By attaching to active predators, the remora delegates the hunting effort to its host, ensuring a consistent supply of food scraps without expending its own energy.