''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. Thei ...

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 Kalk Bay (Afrikaans: ''Kalkbaai'') is a fishing village and suburb of Cape Town. It lies on the west coast of False Bay. Much of the town is built on the slopes of mountains which border the sea, with peaks of Table Mountain Sandstone forming va ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, and subsequently reported from the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it ...

, southwest

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

Clarion Island Clarion Island (), formerly Santa Rosa, is the second largest, westernmost and most remote of Mexico, Mexico's Revillagigedo Islands. The island is located west of Socorro Island and just under from the Mexican mainland. It has an area of an ...

off

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, and

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

. A report from the

Bering Sea The Bering Sea ( , ; rus, Бе́рингово мо́ре, r=Béringovo móre, p=ˈbʲerʲɪnɡəvə ˈmorʲe) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasse ...

may have been in error. It is found in the

bathypelagic zone The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of below the ocean surface. It lies between the mesopelagic above and the abyssopelagic below. The bathypela ...

, 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 con ...

comes from a horn-like supraoccipital process projecting forward of its eyes. The

upper jaw In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxillar ...

is protrusible, and the jaws contain small conical

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

. The

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

runs along the entire length of the body and contains 310-392

soft rays Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology co ...

; the first three to five dorsal rays at the tip of the projecting ridge are elongated into a pennant. The

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s contain 13-15 rays; the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s are absent. The

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

contains five to 9 rays and in adults is split lengthwise to form two rows of nubbins. The

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

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 Lampriformes is an order of ray-finned fish. Members are collectively called lamprids (which is more properly used for the Lampridae) or lampriforms, and unite such open-ocean and partially deep-sea Teleostei as the crestfishes, oarfish, opahs ...

genera known to possess ink tubes, allowing them to expel a black fluid from their

cloaca A cloaca ( ), : cloacae ( or ), or vent, is the rear orifice that serves as the only opening for the digestive (rectum), reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles, birds, cartilagin ...

e as a defense against

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s. 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 tract is the largest of the body's systems, after the cardiovascular system. T ...

. A known

of the unicorn crestfish is the

longnose lancetfish ''Alepisaurus ferox'', also known as 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 Fish measurement, total ...

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

Babelichthys ''Babelichthys'' is an extinct genus of crestfish from the ?Priabonian, Late Eocene-aged Pabdeh Formation of Western Iran. It contains a single species, ''Babelichthys olneyi''. The type specimen was initially figured by Camille Arambourg as a se ...

'', is known from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

of Iran.

References

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