Remora
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| Remora | ||||||||||
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 Spearfish remora, Remora brachyptera
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Echeneis |
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Echeneididae |
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Remoras or suckerfish are elongate brown fish in order Perciformes and family Echeneidae.[1][2] 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.[3] For other species, such as those found in a host's mouth, scavenging of leftovers is more likely. Many sources[citation needed] 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.
[edit] Species
There are eight species in four genera:
- Genus Echeneis
- Live sharksucker, Echeneis naucrates Linnaeus, 1758.
- Whitefin sharksucker, Echeneis neucratoides Zuiew, 1786.
- Genus Phtheirichthys
- Slender suckerfish, Phtheirichthys lineatus (Menzies, 1791).
- Genus Remora
- Whalesucker, Remora australis (Bennett, 1840).
- Spearfish remora, Remora brachyptera (Lowe, 1839).
- Marlin sucker, Remora osteochir (Cuvier, 1829).
- Common remora, Remora remora (Linnaeus, 1758).
- Genus Remorina
[edit] 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,[4] and from northern Australia near Cape York and Torres Strait.[5][6]
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.[7]
[edit] 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.[8]
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.
[edit] References
- ^ "Echeneidae". FishBase. Ed. Rainer Froese and Daniel Pauly. January 2006 version. N.p.: FishBase, 2006.
- ^ Echeneidae (TSN 168567). Integrated Taxonomic Information System. Retrieved on 20 March 2006.
- ^ E. H. Willams et al. (2003). "Echeneid-sirenian associations, with information on sharksucker diet". Journal of Fish Biology 63 (5): 1176–1183. doi:10.1046/j.1095-8649.2003.00236.x.
- ^ E. W. Gudger (1919). "On the Use of the Sucking-Fish for Catching Fish and Turtles: Studies in Echeneis or Remora, II., Part 1.". The American Naturalist 53 (627): 289-311.
- ^ E. W. Gudger (1919). "On the Use of the Sucking-Fish for Catching Fish and Turtles: Studies in Echeneis or Remora, II., Part 2". The American Naturalist 53 (628): 446-467.
- ^ Narrative of the Voyage of H.M.S. Rattlesnake, available at Project Gutenberg. (Dr. Gudger's accounts are more authoritative, but this source is noted as an early account that Gudger appears to have missed.)
- ^ Leo Wiener (1921). "Once more the sucking-fish". The American Naturalist 55 (637): 165-174.
- ^ Pliny the Younger. "Book 32, Chapter 1", Natural History. (cited in E. W. Gudger (1930). "Some old time figures of the shipholder, Echeneis or Remora, holding the ship". Isis 13 (2): 340-352. doi:.
 A Remora and its sucker-like organ |
 A nurse shark with remoras attending |
 A Manta ray with remoras |
