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-- R e m o r a s --
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| Q 1. | ||
| How does the shark sucker attach itself to sharks? |
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| Q 2. | ||
| Do fish ever try to dislodge the pilot fish which sometimes become attached to them? If removed will the pilot fish reattach itself? |
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| Q 3. | ||
| Is a shark sucker considered to be a parasite? |
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| Q 4. | ||
| Recently while fishing I caught what I thought to be a remora. It weighed four pounds. To my embarrassment I told the members of my club that it belongs to the shark family. Can you tell me if this is true and if not, please tell me the family to which it belongs. |
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| Q 5. | ||
| Is it true that in some parts of the world natives use shark suckers to catch other fish? |
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| Q 6. | ||
| I have caught many sailfish and marlin but never noticed any remoras attached to them. On several occasions however, I have found the remoras in the fish well after we had returned to port. Where do these remoras come from? |
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| Q 7. | ||
| I recently caught a strange looking fish with a flat, suction-like disc on the top of its head. I understand that this fish is called a shark sucker and is transported by larger fishes. Can you tell me if this is so? |
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| Q 8. | ||
| What is a pilotfish and what is a sharksucker or remora? |
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| Q 9. | ||
| What is a pilotfish and what is a sharksucker or remora? |
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| Q 10. | ||
| While diving in a reef area near Jensen Beach, we found some cobias staying just above large stingrays which were partially buried under the sand of the ocean floor. Is there a reason why the cobias and stingrays stay together? How big do stingrays get? |
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| Q 11. | ||
| On several occasions when I was sailing a catamaran in water 4 to 9 feet deep off New Providence in the Bahamas, small remoras have attached themselves to the hull. Can remoras exist without sharks? If so-how? |
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| Q 12. | ||
| While snorkeling off the Florida Keys, I was surrounded by a group of 2- to 3-foot-long brown sharklike fish that were escorting a large southern stingray. The fish had a long broad head, with eyes set wide apart. Can you identify them? |
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| Q&A 1. | How does the shark sucker attach itself to sharks? |
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| The shark suckers or remoras (Family Echeneididae) are specially designed for "hitching rides" on other fishes, including sharks, large rays, swordfish, tarpon, and barracuda. The sucking disk, which is actually a modified dorsal fin, consists of an oval pad on the top of the head. Inside the pad is a double row of movable flanges, recalling a Venetian blind. When the flanges are raised on edge, a partial vacuum is formed, and the remora is able to cling firmly to the skin of another fish. Remoras are not to be considered to be parasites, but are mat biologists term "commensals". They accompany larger fish probably for the purpose of feeding on the smaller scraps "Then their "host" makes a kill. |
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| Q&A 2. | Do fish ever try to dislodge the pilot fish which sometimes become attached to them? If removed will the pilot fish reattach itself? Miami Beach, Florida |
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| There is a pilot fish which belongs to the family of jackfish and was so named because sailors who often saw it swimming with sharks imagined that it acted as a pilot to the sharks. But you are probably referring to one of the remoras, fishes that belong to the family Echeneididae. These fishes have the anterior dorsal fin converted into an oval, suctorial disc situated on top of the head and by the means of it they are able to adhere firmly to sharks and other large fishes. They can free themselves at will and then reattach. They also have been known to attach themselves to vessels. The common American species are Echeneis naucrates and Remora remora. An account of the actions of a jewfish and a remora during the period that they were being transported in a tank from Bermuda to New York by the late J. Nelson Gowaploch is enlightening. The remora had attached itself to the jewfish on the dorsal surface back of the head. The jewfish continually tried to scrape the remora off by running under a steel rod which extended across the tank. Each time the remora leaped deftly over the rod and reattached itself to the jewfish in the same place. This continued until it became necessary to remove the remora from the tank because the persistent jewfish was rubbing itself raw. |
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| Q&A 3. | Is a shark sucker considered to be a parasite? Key Biscayne, Florida |
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| The shark suckers or remoras (Fam. Echeneididae) are not parasites, since they do not obtain their food supply directly from the sharks or other fishes to which they are found attached. Instead they are "commensals", which means that they merely live attached to and in association with the larger fishes. The remoras have a remarkable, shield-shaped sucking disk (actually a modification of the dorsal fin) on the top of their heads. By means of this disk, they can slide about freely over the surface of a shark without losing their grip and without apparently bothering the shark in any way. When the shark makes a "kill" the remoras commonly feed on the smaller scraps. Besides sharks, sailfish, spearfish, marlin, barracuda, jacks, whip rays, and even one species of parrot fish are occasionally seen with remoras clinging to their sides. The remora should not be confused with the pilot fish (Naucrates ductor),which is an entirely different type of fish which sometimes swims in company with a shark or other large fish. |
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| Q&A 4. | Recently while fishing I caught what I thought to be a remora. It weighed four pounds. To my embarrassment I told the members of my club that it belongs to the shark family. Can you tell me if this is true and if not, please tell me the family to which it belongs. Miami, Florida |
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| Unfortunately for your reputation, the remoras do not belong to the same family as 'do the sharks. Remoras are bony fish while the shark 's skeleton is composed of cartilage. This and many other differences distinguish these animals as members of two separate groups. The remoras belong to the family Echeneidiae and are characterized by a flat suction disk on top of the head. This disk is laminated like a Venetian blind and is oval in outline. This disk enables the remora to attach firmly to other fishes sf a large size. The sucking disk has considerable power, but these fish are not parasitic. |
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| Q&A 5. | Is it true that in some parts of the world natives use shark suckers to catch other fish? Balboa, California |
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| The habit of the sucking fish or remora to fastening on to other fish has been taken advantage of by man, who actually makes use of the remora to catch other fish. The method is practiced by the natives of the Caribbean Sea, Chinese waters and the Torres Straits. Although sometimes they are used to catch sharks they are chiefly used for capturing turtles. The remora has a thin line attached to its tail. Upon sighting a turtle the natives row up to within easy reach of it and then throw the remora towards it. The fish immediately swims to the turtle and attaches itself to its undersurface. By pulling on the rope, the boat and turtle can then be brought close together and the turtle captured. |
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| Q&A 6. | I have caught many sailfish and marlin but never noticed any remoras attached to them. On several occasions however, I have found the remoras in the fish well after we had returned to port. Where do these remoras come from? Marathon, Florida |
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| The remoras are also known as sucking fishes for by means of an oval adhesive disc on the upper surface of the head (a modified dorsal fin) the fish can attach itself to a flat surface. They are in the habit of attaching to sharks, whales, porpoises and turtles. When a marlin or sailfish is fighting the remora may enter the gill cavity. In the case you mentioned the remora could have been located in the gill cavity of your catch when it was landed and then came out when the catch was placed in the fish box. The remora may obtain some fragments of food floating in the water when it is attached to the bodies of larger swimmers, but it can also detach itself and hunt independently when in good feeding areas. |
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| Q&A 7. | I recently caught a strange looking fish with a flat, suction-like disc on the top of its head. I understand that this fish is called a shark sucker and is transported by larger fishes. Can you tell me if this is so? Queens, New York |
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| The shark sucker, or remora, attaches itself to sharks and other large fish by means of a suctorial disc. This disc, which is situated on the dorsal side of the head, is a modified spiny dorsal fin. The remora has been known to attach itself to the sides of ships in the same manner. The remora usually clings to its host during mealtimes. When the large fish feeds, bits of food float free in the water. Then the remora releases itself and eats the left overs, with no unnecessary energy expended in hunting. Natives of the South Sea Islands tie live remoras to the end of their lines. When a large fish passes, the remora clings to it, and the fisherman hauls them both in. |
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| Q&A 8. | What is a pilotfish and what is a sharksucker or remora? West Palm Beach, Florida |
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| The pilotfish, Naucrates ductor, is a jack that swims with sharks and other large fishes. The relation is a loose and one-sided affair, the pilotfish profiting from the sloppy feeding habits of the others. Pilotfishes are not always in company with other fishes, nor are they the only ones to have this habit. The sharksucker, Echeneis naucrates, is commonly found on many other marine animals besides sharks, including turtles, mullets and parrotfishes. There are other genera and species of remora, several of which attach to sharks. The attachment is a voluntary one and often the remora also swims unattached but close to the "host." Like the pilotfish it picks up- scraps of food and injured small fishes. It has been suggested that they also remove parasites from the host's body. |
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| Q&A 9. | What is a pilotfish and what is a sharksucker or remora? West Palm Beach, Florida |
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| The pilotfish, Naucrates ductor, is a jack that swims with sharks and other large fishes. There is no evidence that a pilotfish will lead a shark to prey, as has been suggested. On the contrary, the relationship appears to be a loose and one-sided one, with the pilotfish benefiting from the sloppy feeding habits of sharks. The pilotfish may also benefit from the protective presence of a large fish and the cover provided by it. For example, a predator might hesitate to dart in and attack a small fish that is swimming a few feet from the jaws of a shark. The sharksucker, Echeneis naucrates, has a suction disk atop its head with which it attaches itself to sharks and other large animals. There are other genera and species of remoras, several of which attach to sharks. Remoras are also found on turtles, billfishes and other animals. Some are quite selective and are found only on a particular species, while others will apparently attach to almost anything of the right size. The attachment is purely voluntary, and remoras are sometimes seen swimming unattached but close to a "host." Like the pilotfish, the remoras pick up scraps of food and injured small fishes. It has been suggested that remoras also pick parasites from the body of their host. An article about remoras appeared in Sea Frontiers, Vol. 9, No.2, May, 1963. |
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| Q&A 10. | While diving in a reef area near Jensen Beach, we found some cobias staying just above large stingrays which were partially buried under the sand of the ocean floor. Is there a reason why the cobias and stingrays stay together? How big do stingrays get? Jensen Beach, Florida |
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| Cobias like many other oceanic fishes (notably, jacks and rudderfishes), frequently associate with large sharks or rays. In so doing, they stand to profit from prey animals that are scattered or killed by the larger fishes, which are usually slower and less maneuverable. Perhaps the cobias you saw were waiting for fishes and crustaceans to dart up in the water column as the stingray disturbed them in its search for burrowing organisms on the ocean bottom. In the case of jacks and rudderfishes, it is usually the smaller individuals that swim near the shark or ray. This suggests that they gain some protection from the larger fishes; that is, the small rudderfishes apparently can avoid, or do not prompt, attack by the shark, but a dolphin could easily catch them if they swam free. The larger stingrays in Florida waters reach 5 to 6 feet across the disk, and up to 14 feet from snout to tail tip. Individuals of this size are not rare, and no doubt an occasional specimen will be somewhat larger. The giant Australian stingray can reach 6 to 7 feet across the wings and weigh 750 pounds. Needless to say, a person should not dive headfirst, or dive in a prone position near the bottom, in areas where stingrays occur. To do so may result in a serious or fatal injury. A description of the venom of stingrays, its effect on humans, and treatment for stingray wounds is given in Living Fishes of the World by E. S. Herald {Doubleday & Company, Inc., New York), and in Volume 2 of Poisonous and Venomous Marine Animals of the World: Vertebrates by B. W. Halstead (U.S. Government Printing Office, 1967). |
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| Q&A 11. | On several occasions when I was sailing a catamaran in water 4 to 9 feet deep off New Providence in the Bahamas, small remoras have attached themselves to the hull. Can remoras exist without sharks? If so-how? Rye, New York |
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| Remoras characteristically hitchhike on larger fishes, such as swordfish, tarpon, sharks; rays, and barracudas. They will cling to any large, moving object for the purpose of feeding on the smaller scraps when their host makes a kill. Remoras are not parasites, but are commensals. This means that they live attached to and associated with larger fishes, but they can also survive without them-often detaching themselves at will and then reattaching to the same or another fish. Some species are very restricted in host selection, occurring with a single type of animal, whereas other species commonly swim free and will attach to a wide variety of fishes, turtles, and even swimmers. |
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| Q&A 12. | While snorkeling off the Florida Keys, I was surrounded by a group of 2- to 3-foot-long brown sharklike fish that were escorting a large southern stingray. The fish had a long broad head, with eyes set wide apart. Can you identify them? Tavernier, Florida |
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| The fish you observed were cobia (Rachycentron canadum). This species is found in all tropical and warm temperate oceans except the eastern Pacific. In the water, it is frequently mistaken for a shark because of the elevated anterior portion of the second dorsal fin and the broad flattened head. Unlike a shark, the cobia possesses separate dorsal spines in front of the well-developed dorsal fin, a crescent-shaped caudal fin, and a lower jaw that projects slightly beyond the upper one. Cobia often escort stingrays over sandy bottoms, feeding on crabs and other crustaceans stirred up by the rays' large wings. In southeast Florida, some charterboat fishermen hire airplane pilots to spot the more visible rays, around which they hope there will be cobia. The cobia is prized as a hard-hitting game fish, with females officially recorded up to 110 pounds. It is also considered an excellent food fish. Its firm, white meat may be baked, broiled, deep-fried, or smoked. |
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Rosenstiel School of Marine & Atmospheric Science Library
University of Miami, FL USA 4600 Rickenbacker Causeway, Miami, Florida 33149 Phone: 305 421 4060 Fax: 305 421 9306 E-mail: libcirc@rsmas.miami.edu |
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