Echeneis naucratesSlender sharksucker

Geographic Range

Sharksuckers, also known as remora, are commonly found in all warm seas. Sharksuckers have been found in the Western Atlantic, from Nova Scotia, Canada through Bermuda and the Gulf of Mexico, to Uruguay. They are found in the Mediterranean Sea. Their presence has also been reported in the Pacific Ocean, north to San Francisco, and Indian Ocean (Tarleton 1903).

Habitat

Echeneis nacurates are often present in shallow inshore brackish areas, as well as around coral reefs. They are found at depths ranging from 20-50 meters, which is where the coral reefs are located (Humann 1994).

There have also been sightings of E. nacurates near Long Island, New Jersey, Massachusetts, and traveling up the Hudson River attached to a host (Smith 1997).

Physical Description

Echeneis naucrates can be easily spotted due to the sucking disc on top of its head. Its sucking organ consists of numerous pairs of crests, which originated from a highly modified spiny dorsal fin. This sucking disc is capable of producing a strong vacuum that the species uses to attach to their hosts. The fish is usually 11 or 12 times as long as it is wide, and about five and a half times the length of its head. The slim body usually has a dark stripe on the side with narrower pale edges (Field 1998). The sharksucker's tail is pointed, and the jaw is protruded. Echeneis naucrates' pectoral and ventral fins are dark in color, and the belly is a dark brownish color. The dorsal and anal fins are black, and are outlined with a lighter shade. Sharksuckers can reach approximately 100 centimeters in length, yet smaller ones are found more frequently. Adult females and males are difficult to distinguish. After the formation of the sucking disc, the young start to resemble the adults (Bigelow 1953).

  • Average mass
    2.01 g
    0.07 oz

Reproduction

Not a lot is known about the reproduction patterns of sharksuckers. Spawning occurs in the warm seasons, spring and early summer in most of its range, and during the autumn in the Mediterranean. The sexes are separate, sperm and eggs develop in male and female individuals. In males, sperm passes from the testis to the outside by a specially developed duct (Lagler et al. 1962). Eggs are fertilized externally then enclosed in a hard shell, which protects them from damage and drying. The eggs can still hatch after they have been washed onto the shore, due to the protective shell that forms around them. Eggs are large, pelagic and spherical in shape. Newly-hatched E. naucrates are 4.7-7.5 mm long, have a large yolk sac, non-pigmented eyes, and an incompletely formed body. Immature fish live freely for approximately one year until they are about 3 cm in length, which is when they attach themselves to a host fish. When the newly-hatched E. naucrates are still developing, the sucking device begins forming. Also, the fish develop small teeth on the upper jaw, and large teeth on the lower jaw. The fish reach sexual maturity within three to five years (Lagler et al. 1962).

Behavior

Echeneis naucrates commonly swim in groups. Sharksuckers are found attached tightly to their hosts from the beginning of their lives (i.e. sharks, snappers, dolphins, turtles, and whales) (Hoese 1977). They are dependant on other organisms in the oceans for their own survival. In this commensal relationship, the E. naucrate's host is not harmed, while the fish benefits greatly. Not only does the fish obtain its food from the host, but it can also save energy because the host is the mode of transportation. Sharksuckers are poor swimmers and lack a swim bladder, they are therefore called "hitchhikers," because they hitchhike rides on other aquatic organisms. Using their modified dorsal fin as a sucking disc, sharksuckers attach themselves onto either the body or the gill area of the host (Debelius 1997).

Sharksuckers have no known predators.

Communication and Perception

Food Habits

The usual diet of sharksuckers is composed of scraps of food that are lost or rejected by the large host animal it is attached to. The fish also feed on small crustacean parasites that invade the skin of the host, and supplement their diet with other free living small crustacea, fishes, crabs and squid (Field 1998).

In captivity, the fish usually remain stationary on the bottom with the head slightly raised, and will rise to the surface to take pieces of clam or fish from the hand (Tarleton 1903).

Economic Importance for Humans: Positive

In the past Echeneis naucrates have been used as an aid in fishing. The fishermen tied lines to the remora and then released them into the deep sea. Since sharksuckers are always on the lookout to attach to a host, they behaved in the same matter when the fishermen dropped them into the water. When the remora found a suitable host and attached to it, the fishermen would haul the line, pulling the sharsucker along with its host onto land. Using E. naucrates as bait is a very intelligent and quick way of capturing bigger edible fish that the remora clings to. This benefits humans because normally hard-to-catch sea organisms are acquired easily (Humann 1994).

Economic Importance for Humans: Negative

Sharksuckers attach with their powerful sucking disc to the bottoms of boats and occasionally to swimmers, causing damage to the boat and maybe even sinking it if the damage is severe enough. Even though very few instances were reported where Echeneis naucrates attached to humans, one can imagine how extremely painful it would be to have the numerous sharp ridges of the sucker clinging onto the human body (Debelius 1997).

Conservation Status

Echeneis naucrates are not listed in IUCN, CITES appendices, or the United States Endangered Species Act list.

Sharksuckers are very common in various oceans. They interact with many other organisms and depend on them for survival (Tarleton 1903).

Other Comments

Sharksuckers were well known to the ancient Greeks, who greatly disliked them. They believed that the Echeneis naucrates had mysterious and magical powers, and were capable of slowing down or even stopping their ships (Debelius 1997).

Contributors

Anna Kowerska (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

tactile

uses touch to communicate

References

Bigelow, B. 1953. Fishes of the Gulf of Mexico. Washington: United States Government Printing Office.

Debelius, H. 1997. Mediterranean and Atlantic Fish Guide. Frankfurt: IKAN-Unterwasserarchiv.

Field, R. 1998. Reef Fishes of the Red Sea, A guide to Identification. NY, NY: Kegan Paul International.

Hoese, H. 1977. Fishes of the Gulf of Mexico. Texas: Texas A&M University Press.

Humann, P. 1994. Reef fish identification: Florida, Caribbean, Bahamas. Jacksonville, Florida: New World Publications.

Lagler, K., J. Bardach, R. Miller. 1962. Ichthyology. Michigan: John Wiley & Sons, Inc..

Smith, L. 1997. National Audubon Society field guide to tropical marine fishes of the Caribbean, the Gulf of Mexico, Florida, the Bahams, and Bermuda. New York: Knopf, Inc..

Tarleton, B. 1903. Catalogue of the Fishes of New York. Albany: New York State Museum.