Common name: Hammerjaws, Lancetfishes and Omosudids


Alepisaurids are predatory deep sea fishes with huge fang-like teeth. The famliy comprises the large, predatory oceanic lancetfishes of the genus Alepisaurus, and the smaller Hammerjaw, Omosudis.

Cite this page as:
Dianne J. Bray, Lancetfishes ..., ALEPISAURIDAE in Fishes of Australia, accessed 20 Jun 2024,

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Family Taxonomy

A very small family with two genera and three species, all found in Australian waters. Prior to Baldwin & Johnson (1996) including Omosudis in the Alepisauridae, Alepisaurus and Omosudis were placed in their own separate families.

Family Distribution

Found worldwide in all oceans, from tropical to subarctic and subantarctic waters. Alepisaurids are primarily meso- and bathypelagic fishes. Lancetfishes reach depths of more than 1800 metres, whereas the Hammerjaw has been recorded from bathypelagic waters down to 4000 metres. The genus Alepisaurus has been recorded from surface waters.

Family Description

Meristic features: D 30-35; A 13-18; P 12-15; V 8-10; GR (2-6)+(16-24); Principal caudal rays 9+10; Vertebrae 47-52; BR 7-8.

Elongate, slender, slightly compressed deepwater fishes with clear adipose tissue on the circular, laterally-directed eyes; small dorsal adipose fin near tail; anal fin low, short-based; forked caudal fin preceded by a low, somewhat flaccid midlateral keel. 

Alepisaurus: Body elongate, somewhat compressed, dorsal fin high, sail-like along most of back; midlateral keel present along most of rear half of side of body; head pointed; palatine with 1–2 large fangs anteriorly, about 3 smaller fangs and 7–10 triangular teeth posteriorly; upper jaw teeth small, lower jaw with large anterior fang followed by about 10 small canines, up to 3 large fangs and 10–15 low triangular teeth; vertical adipose tissue at front and rear of eye; pectoral fin pointed.

Omosudis: Head blunt; anterior end of lower jaw deep; teeth on jaws, palatine and pharyngeals only, in single row on jaws; lower jaw with prominent slender canines, one considerably longer than rest; upper jaw with small canines along edge and several pairs of large slender canines on palatine; short-based dorsal fin near middle of back; lateral dermal keel on side of caudal peduncle above rear half of anal fin; lateral line absent.

Family Size

Omosudis only reaches a length of about 30 cm, whereas Alepisaurus grows to a length of more than 2 metres.

Family Colour

The Hammerjaw is iridescent silvery-bronze in colour.

Family Feeding

With their large mouths and huge fangs, Lancetfishes (Alepisaurus) are some of the largest and most voracious predators in the deepsea. They feed on a variety of mesopelagic fishes, cephalopods, crustaceans, jellyfish and tunicates, and may have even destroyed underwater cables. The smaller Hammerjaw (Omosudis) is also a voracious predator, feeding on small midwater fishes and cephalopods.

Family Reproduction

Alepisaurids are synchronous hermaphrodites, possessing both male and female reproductive tissue at the same time. This reproductive strategy is very useful in the deep sea where population densities are low. Fertilization is external, eggs are unknown and larvae are planktonic.

Family Commercial

Alepisaurus is often taken as bycatch in commercial longline tuna fisheries in epipelagic waters. Although edible, the flesh is watery and unsuitable for commercial production.

Family Conservation

IUCN: Not evaluated.

Family Remarks

Images, including MRI scans of the Longnose Lancetfish, Alepisaurus ferox, can be viewed on line at the Digital Fish Library. Alepisauridae means "scaless lizard" and is from the Greek a, meaning "without", lepis meaning "scale" and sauros meaning "lizard".


Dianne J. Bray

Family Resources

Catalog of fishes


Ambrose, D.A. 1996. Alepisauridae: lancetfishes. p. 379-381. In Moser, H.G. (ed.) The early stages of fishes in the California Current region. California Cooperative Oceanic Fisheries Investigations (CalCOFI) Atlas No. 33. 1505 pp.

Baldwin, C.C. & Johnson, G.D. 1996. Interrelationships of Aulopiformes. pp. 355-404. In Stiassny, M.L.J., Parenti, L.R. & Johnson, G.D. (eds). Interrelationships of Fishes. San Diego : Academic Press 496 pp.

Bray, D.J. 2008. Alepisauridae. In Gomon, M.F., D.J. Bray & R.H. Kuiter. Fishes of Australia’s Southern Coast. Reed new Holland, Chatswood, Australia.

Ditty, J.G. 2006. Chapter 31: Alepisauridae: Lancetfishes. In Richards, W.J. Early stages of Atlantic fishes: an identification guide for the Western Central Atlantic. 1: 367-373, CRC Press, Boca Raton, Floridae, 1335pp.

Ege, V. 1958. Omosudis Günther, bathypelagic genus of fish. 'Dana' Reports 47: 1-19 figs 1-3.

Francis, M.P. 1981. Meristic and morphometric variation in the lancet fish Alepisaurus, with notes on the distribution of A. ferox and A. brevirostris. New Zealand Journal of Zoology 8(3): 403-408 fig. 1

Gibbs, R.H. 1960. Alepisaurus brevirostris, a new species of lanternfish from the western North Atlantic. Breviora (123):1-14.

Gon, O. 1990 Alepisauridae. p. 144-145. In Gon, O. & P.C. Heemstra (eds.) Fishes of the Southern Ocean. J.L.B. Smith Institute of Ichthyology, Grahamstown, South Africa.

Gibbs, R.H. & Wilimovsky, N.J. 1966. Family Alepisauridae in Olsen, Y.H. (ed.) Fishes of the western North Atlantic. Memoir. Sears Foundation of Marine Research 1(5): 482-497 figs 173-176.

Heemstra, P.C. & M.M. Smith, 1986 Alepisauridae. p. 280-281. In Smith, M.M. & P.C. Heemstra (eds.) Smiths' sea fishes.

Hoese, D.F., D.J. Bray, J.R. Paxton & G.R. Allen, 2006 Fishes. In Beesley, P.L. & A. Wells (eds.) Zoological Catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia Parts 1-3.

Ichthyoplankton Information System. 23 July 2009. Alepisaurus ferox, National Oceanic and Atmospheric Administration. (20 July 2010)

Moteki, M., K. Fujita & H. Kohno, 1993 Stomach contents of longnose lancetfish, Alepisaurus ferox, in Hawaiian and central equatorial Pacific waters. J. Tokyo Univ. of Fish. 80(1):121-137.

Okiyama, M. 1984. Myctophiformes: Relationships. In Moser, H.G., W.J. Richards, D.M. Cohen, M.P. Fahay, A.W. Kendall, Jr. & S.L. Richardson (eds.) Ontogeny and Systematics of Fishes. Spec. Publ. No. 1: 254-259. American Society of Ichthyologists and Herpetologists, Lawrence, KS.

Orlov, A.M. & V.A. Ul'chenko. 2002. A hypothesis to explain onshore records of long-nose lancetfish Alepisaurus ferox (Alepisauridae, Teleostei) in the North Pacific Ocean. Mar. Freshwater Res. 53: 303-306.

Paxton, J.R. & V.H. Niem 1999. Omosudidae. In Carpenter, K.E. & V.H. Niem (Eds). FAO Species Identification Guide for Fishery Purposes. The Living Marine Resources of the Western Central Pacific. Volume 3. Batoid fishes, chimaeras and bony fishes part 1 (Elopidae to Linophrynidae). FAO, Rome. Pp. iii-vi, 1398-2068.

Rofen, R.R. 1966. Family Omosudidae. In, Olsen, Y.H. (ed.) Fishes of the western North Atlantic. Memoir. Sears Foundation of Marine Research 1(5): 462-481 figs 163-172.

Romanov, E.V. & V.V. Zamorov. 2002. First record of a yellowfin tuna (Thunnus albacares) from the stomach of a longnose lancetfish (Alepisaurus ferox). Fish. Bull. 100(2): 386-389.

Romanov, E.V. & V.V. Zamorov. 2007. Regional feeding patterns of the Longnose Lancetfish (Alepisaurus ferox Lowe, 1833) of the Western Indian Ocean. Western Indian Ocean J. Mar. Sci. 6(1): 37-56.

 Romanov, E.V., F. Ménard, V.V. Zamorov & M. Potier. 2008. Variability in conspecific predation among longnose lancetfish Alepisaurus ferox in the western Indian Ocean. Fish. Sci. 74: 62-68.

Smith, C.L. & Atz, E.H. 1973. Hermaphroditism in the mesopelagic fishes Omosudis lowei and Alepisaurus ferox. Copeia 1973(1): 41-44, fig. 1.