Family STERNOPTYCHIDAE


Common name: Marine Hatchetfishes

Silhouette

Summary:

Family of small, silvery bioluminescent fishes living the deep oceanic midwaters. Many species have extremely compressed bodies with a deep keel, large eyes, upturned mouths and groups of photophores along the ventral surface and lower sides of the head and body.

Marine hatchetfishes are very well-camouflaged for life in the oceanic 'twilight' zone. The combination of very silvery sides, downwardly-directed photophores and a darkly-pigmented dorsal surface disrupts their body silhouette, hiding them from predators and prey.

Many species undertake daily vertical migrations to feed at night in shallower waters where food is more plentiful.


Cite this page as:
Dianne J. Bray, Marine Hatchetfishes, STERNOPTYCHIDAE in Fishes of Australia, accessed 23 Nov 2017, http://fishesofaustralia.net.au/Home/family/287

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Family Taxonomy

Family with 10 genera and about 75 species in two subfamiles. Twenty-two described species in 6 genera are known from Australian waters.

Family Distribution

Found worldwide in temperate and tropical parts of all oceans. Although most species are mesopelagic, some are bathy- or benthopelagic. Species are found at depths of 100-1260 m, usually below 400 m during the day.

Many sternoptychids undertake diurnal vertical migrations to feed at night in shallower waters where food is more plentiful, returning to deeper waters during the day.

Family Description

Body moderately elongate to very compressed and deep; prominent photophores ventrolaterally on head and body, some series united into distinct clusters of two or more photophores.

Head large, snout short, eyes large, sometimes tubular, eye diameter greater than snout length; mouth small, nearly vertical in some, jaw teeth small; gill rakers well-developed, pseudobranch present, photophores present on branchiostegals.

Dorsal fin small, originating about midbody; dorsal adipose fin if present often low, with an elongate base; bony pectoral-fin radials 4.

Subfamily Sternoptychinae with an abdominal keel-like structure and speciealixed dorsal pterygiophores forming a blade-like structure before the dorsal fin. Scales cycloid, very thin, weakly attached. Sides of body often strickingly silver.

Family Size

to about 10 cm.

Family Feeding

Mesopelagic planktivores feeding on small planktonic crustaceans such as copepods, amphipods and eupahisids.

Family Reproduction

Marine hatchetfishes are oviparous (egg-layers) with planktonic eggs and larvae.

Eggs and larvae of the Subfamily Sternoptychinae are poorly known as they are usually found below 200 m where there has been little collecting with plankton nets.

Larvae of several species of the Subfamily Maurolicinae are usually found in shallower waters and are well-known. Eggs small, buoyant, 0.5-1.65 mm diameter. Larvae long, slender at hatching, some become very deep-bodied with long tails, others remaining slender. Larval identification is based on photophore patterns, fin position and fin-ray counts; photophores develop gradually, some coalesce into gland-like structures.

Family Remarks

Hatchetfishes are very well-camouflaged for life in deep waters of the open ocean. The combination of very silvery sides, downwardly-directed photophores and a darkly-pigmented dorsal surface disrupts their body silhouette, hiding them from predators.

The light emitted from the photophores is thought to match that filtering down from above, so that predators looking upwards cannot see the body outline.

Some species have evolved tubular eyes with large lenses which improve the vision by concentrating the dim light of the deep-sea.

Author

Dianne J. Bray

References


Ahlstrom, E.H., W.J. Richards & S.H. Weitzman. 1984. Families Gonostomatidae, Sternoptychidae, and associated stomiiform groups: development and relationships, pp. 184-198 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. Am. Soc. Ichthyol. Herpetol. Spec. Publ. No. 1, 760 pp.

Baird, R.C. 1971. The systematics, distribution, and zoogeography of the marine hatchetfishes (family Sternoptychidae). Bull. Mus. Comp. Zool. 142(1): 1-128.

Borodulina, O.D. 1978. Materials on the systematics and distribution of the oceanic hatchet fishes genera Argyropelecus and Sternoptyx (Sternoptychidae, Osteichthyes). Trudy Inst. Oceanogr. SSSR 111: 28-60.

Borodulina, O.D. 1979. Composition of the species complex Polyipnus spinosus G√ľnther (Sternoptychidae, Osteichtyes) with descriptions of three new species. Voprosy Ikhtiol. 19(2): 198-208. [In Russian. English transl. in J. Ichthyol. 19(2):1-10.]

Harold, A.S. 1994. A taxonomic revision of the sternoptychid genus Polyipnus (Teleostei: Stomiiformes) with an analysis of phylogenetic relationships. Bull. Mar. Sci. 54(2): 428-534.

Harold, A.S. 1999. Gonostomatidae, Sternoptychidae, Phosichthyidae, Astronesthidae, Stomiidae, Chauliodontidae, Melanostomiidae, Idiacanthidae, and Malacosteidae, pp. 1896-1917. In Carpenter, K.E. & V.H. Niem (eds.) The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Vol 3. FAO, Rome

Harold, A.S. & S.H. Weitzman. 1996. Interrelationships of stomiiform fishes, pp. 333-353. In Stiassny, M.L.J., L.R. Parenti & G.D. Johnson (eds.) The Interrelationships of Fishes. Academic Press, London.

Parin, N.V.& S.G. Kobyliansky. 1993. Review of the genus Maurolicus (Sternoptychidae, Stomiiformes), with re-establishing validity of five species considered junior synonyms of M. muelleri and descriptions of nine new species. Trans. P. P. Shirshov Inst. Oceanol. 128: 69-107.

Parin, N.V. & S.G. Kobyliansky. 1996. Diagnoses and distribution of fifteen species recognized in genus Maurolicus Cocco (Sternoptychidae, Stomiiformes) with a key to their identification. Cybium 20(2): 185-195.

Richards, W.J. 2006. Ch. 18 Sternoptychidae: Marine Hatchetfishes & relatives, p. 217, In W.J. Richards (ed). Early Stages Of Atlantic Fishes: An Identification Guide For The Western Central North Atlantic. CRC Press, Taylor and Francis Group, Boca Raton, FL, 2640 pp.

Weitzman, S.H. 1974. Osteology and evolutionary relationships of the Sternoptychidae with a new classification of stomiatoid families. Bull. Am. Mus. Nat. Hist. 153(3): 327-478.