The common remora, Remora remora, is a pelagic

Pelagic zone

Any water in a sea or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes...

 marine fish belonging to family Echeneidae. Remora remora is different from other remoras in the family Echeneidae by the modification of its dorsal fin. The dorsal fin, which has 22 to 26 soft rays, acts like a suction cup

Suction cup

A suction cup, also sometimes known as a sucker is an object that uses negative fluid pressure of air or water to adhere to nonporous surfaces. They exist both as artificially created devices, and as anatomical traits of some animals such as octopi and squid.The working face of the suction cup has...

, creating a vacuum

Vacuum

In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

 that allows it to attach to larger marine animals such as whales, dolphins, sharks and sea turtles.

Physical characteristics

The common remora has a suckerlike dorsal fin and an anal fin. Its body can be brown, black or grey in color.

Biology and behavior

Remora remora and its host seem to partake in a symbiotic relationship

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

; the common remora does not seem to have a negative effect on its host. The host provides the remora with fast moving water to bathe its gills, a steady flow of food, transportation, and protection. The common remora's attachment to one host can last for up to 3 months. During this time, the remora can move its attachment site if it feels threatened. The common remora cannot survive in still water; it needs water flow over its gills to provide it oxygen.

Habitat

This remora is commonly found in warm marine waters and have been seen in the Western Mediterranean, the Atlantic, as well as the North Sea.

Reproduction

It has been suggested that a mating couple may attach to the same host, and have host fidelity. It is not clear when during the year the common remora spawns

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

, and little else is known about the fish's reproductive behavior.

Food and diet

The remora consumes food scraps from its host, as well as plankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

 and parasitic copepod

Copepod

Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

s.

Significance to humans

There are no known negative impacts for humans. Remoras can be caught as fishing bycatch

Bycatch

The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...

 and put in aquaria

Aquaria

Aquaria may refer to:*Aquarium, in the plural*Aquaria , a computer game*Aquaria , a Brazilian metal band*Aquaria, one of the Twelve Colonies in Battlestar Galactica...

. Remoras have been used in fishing. Humans may attach fishing line

Fishing line

A fishing line is a cord used or made for angling. Important parameters of a fishing line are its length, material, and weight...

to the remora and waiting for it to cling to a larger fish.