''Eumecichthys fiski'', the unicorn crestfish or unicornfish, is a very rare, little-known species of

crestfish Crestfishes, family Lophotidae, are lampriform fishes found in most oceans. It consists of two extant and four extinct genera. They are elongated, ribbon-like fishes, silver in color, found in deep tropical and subtropical waters worldwide. Their ...

in the family Lophotidae, and the only member of the genus ''Eumecichthys''. It likely has a worldwide distribution, having been first discovered offshore of Kalk Bay, South Africa, and subsequently reported from the Sea of Japan, southwest Florida, Clarion Island off Mexico, Hawaii, and India. A report from the

Bering Sea The Bering Sea (, ; rus, Бе́рингово мо́ре, r=Béringovo móre) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasses on Earth: Eurasia and The Ameri ...

may have been in error. It is found in the bathypelagic zone, at a depth of around 1,000 m (3,300 ft). This fish has ribbon-like body measuring up to 150 cm (59 in) in length. Its

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

comes from a horn-like supraoccipital process projecting forward of its eyes. The upper jaw is protrusible, and the jaws contain small conical teeth. The dorsal fin runs along the entire length of the body and contains 310-392 soft rays; the first three to five dorsal rays at the tip of the projecting ridge are elongated into a pennant. The pectoral fins contain 13-15 rays; the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s are absent. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

contains five to 9 rays and in adults is split lengthwise to form two rows of nubbins. The caudal fin contains 12-13 rays, with the bottommost ray enlarged and bony. The coloration is silvery with 24-60 dark subvertical bands. The dorsal and caudal fins are crimson. ''Eumenichthys'' is one of three lampriform genera known to possess ink tubes, allowing them to expel a black fluid from their

cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

e as a defense against predators. The ink tube is derived from a primitive gut and runs above and parallel to the

intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...

. A known predator of the unicorn crestfish is the

longnose lancetfish ''Alepisaurus ferox'', the long snouted lancetfish, longnose lancetfish, or cannibal fish, is a species of lancetfish found in the ocean depths down to 1,830 m (6,000 ft). This species grows to in total length and a weight of . It is ...

(''Alepisaurus ferox''); a lancetfish 73 cm (29 in) long has been found that had swallowed a unicorn crestfish 55 cm (22 in) long.

References

{{Taxonbar, from=Q137988 Lophotidae Monotypic ray-finned fish genera Fish described in 1890