Definitions

remora

remora

[rem-er-uh]
remora, any of the several species of warmwater fishes of the family Echeneidae, characterized by an oval sucking disk on the top of the head. With this apparatus (a modification of the dorsal fin) the remora, or suckerfish, attaches itself to sharks, swordfishes, drums, marlins, and sea turtles. In this way it travels without effort, feeding on scraps from the prey of these larger creatures and in some cases on their crustacean parasites. Remoras sometimes attach themselves to small boats, but they can also swim well on their own. The adhesive power of their sucking disks is so great that the natives of some tropical regions use remoras to catch sea turtles by attaching lines to their tails. Different species prefer different hosts. The whalesucker, Remilegia australis, is usually found attached to whales. The smallest remora, the 7 in. (18 cm) Remoropsis pallidus, prefers swordfishes and tuna. Largest and most common is the shark remora, or sharksucker, which reaches 3 ft (90 cm) in length and attaches itself to sharks; it is found along the Atlantic coast N of Long Island in the summer. Remoras are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Echeniformes, family Echeneidae.
or sharksucker or suckerfish

A remora (Echeneis naucrates) and its host, a zebra shark (Stegostoma fasciatum).

Any of 8–10 species of marine fishes (family Echeneidae) noted for attaching themselves to, and riding about on, sharks, other marine animals, and oceangoing ships. Remoras adhere by means of a flat, oval sucking disk on top of the head. They are thin and dark, 1–3 ft (30–90 cm) long. They live in warm waters worldwide, feeding on the leavings or the external parasites of their hosts.

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Remoras or suckerfish are elongate brown fish in order Perciformes and family Echeneidae. They grow up to 30–90 centimetres long (1–3 ft), and their distinctive first dorsal fin takes the form of a modified oval sucker-like organ with slat-like structures that open and close to create suction and take a firm hold against 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. They also swim well on their own, with a sinuous motion.

Remoras are primarily tropical open-ocean dwellers, occasionally found in temperate or coastal waters if they have attached to large fish that have wandered into these areas. In the mid-Atlantic, spawning usually takes place in June and July; in the Mediterranean, in August and September. The sucking disc begins to show when the young fish are about 1 centimetre long. When the remora reaches about 3 centimetres, the disc is fully formed and the remora is then able to hitch a ride. The remora's lower jaw projects beyond the upper, and there is no swim bladder.

Some remoras associate primarily with specific host species. Remoras are commonly found attached to sharks, manta rays, whales, turtles, and dugong (hence the common names sharksucker and whalesucker). Smaller remoras also fasten onto fish like tuna and swordfish, and some small remoras travel in the mouths or gills of large manta rays, ocean sunfish, swordfish, and sailfish.

The relationship between remoras and their hosts is most often taken to be one of commensalism, specifically phoresy. The host they attach to for transport gains nothing from the relationship, but also loses little. The remora benefits by using the host as transport and protection and also feeds on materials dropped by the host. There is some controversy over whether a remora's diet is primarily leftover fragments, or actually the feces of the host. In some species (Echeneis naucrates and E. neucratoides) consumption of host feces is strongly indicated in gut dissections. For other species, such as those found in a host's mouth, scavenging of leftovers is more likely. Many sources also suggest that for some remora/host pairings the relationship is closer to mutualism, with the remora cleaning bacteria and other parasites from the host.

Species

There are eight species in four genera:

The fishing fish

Some cultures have used remoras to catch turtles. A cord or rope is fastened to the remora's tail, and when a turtle is sighted the fish is released from 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 in. Smaller turtles can be pulled completely into the boat by this method, while larger ones are hauled within harpooning range. This practice has been reported throughout the Indian Ocean, especially from eastern Africa near Zanzibar and Mozambique, and from northern Australia near Cape York and Torres Strait.

Similar reports have also come from Japan and from the Americas. In fact, some of the first records of the "fishing fish" in the Western literature come from the accounts of the second voyage of Christopher Columbus. However, Leo Wiener considers the Columbus accounts to be apocryphal: what was taken for accounts of the Americas may have in fact been notes that Columbus derived from accounts of the East Indies, his desired destination.

Mythology

In ancient times, the remora was believed to stop a ship from sailing. In Latin remora means "delay," while the genus name Echeneis comes from Greek echein ("to hold") and naus ("a ship"). Particularly notable is the account of Pliny the Younger, in which the remora is blamed for the defeat of Mark Antony at the Battle of Actium and (indirectly) for the death of Caligula.

Because of the shape of the jaws, appearance of the sucker, and coloration of the remora, it sometimes appears to be swimming upside-down. This probably led to the older common name reversus, although this might also derive from the fact that the remora frequently attaches itself to the tops of manta rays or other fish, so that the remora in fact is upside-down while attached.

References

External links

National Aquarium Article About Remoras

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