Remora remora, the Common Remora (a.k.a. Suckerfish, Shark-Sucker and Common Sucker) is a pelagic marine fish belonging to the family Echeneidae, that of ray-finned fish. This remora is commonly found in warm marine waters and have also been seen in the western Mediterranean Sea.
In ancient times, the remora was believed to stop a ship from sailing. In Latin, remora means ‘delay’, while the family name Echeneis comes from Greek εχειν, echein (‘to hold’) and ναυς, naus (‘a ship’). In a notable account by Pliny the Elder, the remora is blamed for the defeat of Mark Antony at the Battle of Actium, and indirectly, for the death of Caligula.
The genus Remora belongs to the family Echeneidae, order Carangiformes, class Actinopterygii, phylum Chordata and kingdom Animalia.
Remora remora’s body can be brown, black or grey in colour. This species can reach 86.4 centimetres in total length, though most do not exceed 40 cm. The maximum known weight of this species is 1.1 kg. The Remora remora’s lower jaw projects beyond the upper, and the animal lacks a swim bladder. It swims well on its own, with a sinuous, or curved, motion.
The Common Remora has a sucker-like dorsal fin and an anal fin. The dorsal fin has 22 to 26 soft rays. Its distinctive first dorsal fins take the form of a modified oval, sucker-like organ with slat-like structures that open and close. These act like a suction cup, creating a vacuum and taking a firm hold. The disk is made up of stout, flexible membranes that can be raised and lowered to generate suction. By sliding backward, the remora can increase the suction, or it can release itself by swimming forward.
Remora remora front dorsal fins have evolved to enable them to adhere by suction to smooth surfaces and they spend their lives clinging to a host animal such as a whale, turtle, shark or ray. They are also known to attach to small boats and have been observed attaching to divers as well.
The Common Remora and its host seem to partake in a symbiotic relationship; the Common Remora does not seem to have a negative overall 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 remora benefits the host by feeding in part on some of its parasites, but increases its hydrodynamical drag. The Common Remora’s attachment to one host can last for up to three 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.
Remora remora’s diet is composed primarily of host faeces, as well as plankton and parasitic copepods. A mating couple may attach to the same host, having host fidelity. In the mid-Atlantic Ocean, spawning usually takes place in June and July; in the Mediterranean Sea, it occurs in August and September.
The photo of this Common Remora was taken at a depth of 10m at Xlendi Reef on Gozo’s west coast.
Photo taken by Brian Azzopardi