Remora

Remora are long, slender brown fish (order Perciformes, family Echeneidae[?]) 30-90 cm long (1-3 feet) with a modified dorsal fin used as an oval sucker-like attachment organ with slat-like structures that open and close to take a firm hold on the skin of larger marine animals. By sliding backward, the remora can increase the suction, or it can release itself by swimming forward. Remoras sometimes attach themselves to small boats, but they can also swim well on their own.

They are commonly found attached to sharks, manta rays[?], whales and turtles, using them as transport and protection and also obtaining food from fragments dropped by the host. Smaller remoras also fasten onto fishes like tuna and swordfish, and some small remoras travel in the mouths or gills of large manta rays, ocean sunfish, swordfish, and sailfish[?]. It is thought that they may be helping themselves to the host’s food, but it has also been suggested that they eat parasites in these fish. Certain types of remoras are found almost exclusively on specific animals (e.g. a species called the "whalesucker" attaches only to whales; a shark sucker attaches only to sharks). There are 8-10 species of remora.

The relationship between remoras their host is one of commensalism. The host they attach to for transport gains nothing from the relationship, but it also loses little aside from some extra drag while swimming.

Remoras are primarily a tropical open-ocean dweller, occasionally found in temperate waters in summer because they are attached to large fish that have wandered into cooler areas. In the mid-Atlantic, spawning usually takes place in June and July; in the Mediterranean, in August and September. The sucker begins to show when the young fish are about 0.75 inches long, and young remora are able to hitch a ride when they are about 1.5 inches long.

History

In ancient times, the remora was believed to stop a ship from sailing and was called "ship-holder." Remoras have been used for catching turtles in Central America, Japan, East Africa, and northern Australia[?]. A ring is fitted to the remora’s tail with a cord or rope tied to the ring, and when a turtle is sighted the fish is dropped over the side of the boat; it usually heads directly for the turtle and fastens itself to the turtle’s shell, and then both remora and turtle are hauled back into the boat.