Overview

Brief Summary

The Unicorn Crestfish (Eumecichthys fiski) is the only species in the genus Eumecichthys, which is one of just two genera in the oceanic family Lophotidae (the crestfishes). This species is rare and known only from the deep sea (possibly around 1000 m), but is apparently widely distributed from South Africa to India, Japan, Hawaii, and Mexico. The head and body are silvery with 24 to 60 dark vertical bands and the fins are red. The highly elongated body may reach 130 cm or more (body depth is around 1/25th of length). The first three or four dorsal rays are produced into a long, narrow pennant that extends far forward of the mouth. The dorsal fin includes 310 to 393 rays, the anal fin 5 to 9 rays, the pectoral fin 13 to 15 rays, and the caudal fin (tail) 12 to 13 rays. (Robins and Ray 1986; Heemstra 2003; Froese and Pauly 2011)

The common name, Unicorn Crestfish, comes from the distinctive projecting supraoccipital, a bone on the dorsal (upper) side of the skull.

A unique feature shared by members of the Lophotidae (Lophotes and Eumecichthys) is the presence of an ink tube (or ink sac). The ink tube allows its bearer to expel black fluid from the cloaca as a defense against predators (Robins and Ray 1986; Honma, Ushiki, and Takeda, 1998).

  • Froese, R. and D. Pauly, eds. 2011. FishBase. World Wide Web electronic publication. www.fishbase.org, version (12/2011)
  • Heemstra, P.C. 2003. P. 402 in: Smiths’ Sea Fishes (M.M. Smith and P.C. Heemstra, eds.). Struik Publishers, Cape Town, South Africa.
  • Honma, Y., T. Ushiki, and M. Takeda. 1998. Histology of the ink tube and its associated organs in a unicornfish, Eumecichthys fiskii (Lampridiformes). Ichthyological Research 46(1): 19-25.
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Comprehensive Description

Biology

A rare (Ref. 4165), mesopelagic species found at 1,000 m depth (Ref. 5213).
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Distribution

Probably worldwide. Western Atlantic: southeastern Florida in USA. Southeast Atlantic: False Bay, South Africa (Ref. 4165). Northwest Pacific: Japan (Ref. 559). Eastern Central Pacific: Hawaii and Mexico (Ref. 4165). Indian Ocean: India (Ref. 4165).
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Circumglobal.
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Physical Description

Morphology

Dorsal spines (total): 0; Analspines: 0; Analsoft rays: 5 - 9
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Size

Maximum size: 1500 mm TL
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Max. size

150 cm TL (male/unsexed; (Ref. 7251))
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Diagnostic Description

Description

Mesopelagic species found at 1000 m depth (Ref. 5213). Rare species (Ref. 559).
  • Anon. (1996). FishBase 96 [CD-ROM]. ICLARM: Los Baños, Philippines. 1 cd-rom pp.
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Head and body silvery in color with 24-60 dark sub vertical bands; dorsal and caudal fins crimson in color (Ref. 4165). Dorsal fin with 310-392 soft rays.
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Ecology

Habitat

Environment

bathypelagic; marine
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Depth range based on 2 specimens in 1 taxon.
Water temperature and chemistry ranges based on 1 sample.

Environmental ranges
  Depth range (m): 33.5 - 100
  Temperature range (°C): 24.323 - 24.323
  Nitrate (umol/L): 0.757 - 0.757
  Salinity (PPS): 36.186 - 36.186
  Oxygen (ml/l): 4.519 - 4.519
  Phosphate (umol/l): 0.118 - 0.118
  Silicate (umol/l): 1.328 - 1.328

Graphical representation

Depth range (m): 33.5 - 100
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Conservation

Threats

Not Evaluated
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Wikipedia

Unicorn crestfish

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. 
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