Unicorn crestfish

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Unicorn crestfish
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lampriformes
Family: Lophotidae
Genus: Eumecichthys
Regan, 1907
Species: E. fiski
Binomial name
Eumecichthys fiski
(Günther, 1890)
Synonyms

Lophotes fiski Günther, 1890

The unicorn crestfish or unicornfish, Eumecichthys fiski, is a very rare, little-known species of crestfish in the family Lophotidae, and the only member of its genus. 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 may have been in error. It is found in the bathypelagic zone, at a depth of around 1,000 m (3,300 ft).[1][2]

The head of a unicorn crestfish.

This fish has ribbon-like body measuring up to 150 cm (59 in) in length.[1] Its common name comes from a horn-like supraoccipital process projecting forward of its eyes.[3] The upper jaw is protrusible, and the jaws contain small conical teeth.[4] 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 fins are absent. The anal fin 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.[5]

Eumenichthys is one of three lampriform genera known to possess ink tubes, allowing them to expel a black fluid from their cloacae as a defense against predators. The ink tube is derived from a primitive gut and runs above and parallel to the intestine.[2] A known predator of the unicorn crestfish is the longnose lancetfish, (Alepisaurus ferox); a lancetfish 73 cm (29 in) long has been found that had swallowed a unicorn crestfish 55 cm (22 in) long.[6]

References[edit]

  1. ^ a b Froese, Rainer and Pauly, Daniel, eds. (2009). "Eumecichthys fiski" in FishBase. March 2009 version.
  2. ^ a b Honma, Yoshiharu; Ushiki, Tatsuo; Takeda, Masaei (Feb 1999). "Histology of the ink tube and its associated organs in a unicornfish, Eumecichthys fiskii (Lampridiformes)". Ichthyological Research 46 (1): 19–25. doi:10.1007/BF02674944. 
  3. ^ Richards, W.J. (2006). Early stages of Atlantic fishes: an identification guide for the western central North Atlantic. CRC Press. ISBN 9780849319167. 
  4. ^ Olney, J.E. (1998). "Lophotidae". In Carpenter, K.E. and Niem, V.H. FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Food and Agricultural Organization of the United Nations. ISBN 92-5-104302-7. 
  5. ^ Smith, J.L.B., Smith, M.M. and Heemstra, P. (2003). Smiths' Sea Fishes. Struik. ISBN 1-86872-890-0. 
  6. ^ Fujita, K. and Hattori, J. (1976). "Stomach Content Analysis of Longnose Lancetfish, Alepisaurus ferox in the Eastern Indian Ocean and the Coral Sea". Japanese Journal of Ichthyology 23 (3): 133–142.