Family Stomiidae

Taxonomy: 28 genera with about 273 species; about 64 species in 19 genera known from Australian waters.

Distribution, ecology and habitat: Midwater predators of all oceans; epi-, meso- to bathypelagic in the open ocean to 4500 m, adults of a few migrate to surface waters at night.

Characteristics:
All subfamilies share the following characters: Body elongate, serial photophore rows on abdomen; true gill rakers absent in adults, one infraorbital bone (vs two in other stomiiforms), supramaxillary single if present, mesopterygoid reduced or absent, most with a chin barbel associated with hyoid bone and tipped with a bioluminescent lure. Mouth large, often with fang-like teeth.

Subfamily Astronesthinae (Snaggletooths): Scales absent, dorsal-fin origin at about midbody, over or behind pelvic-fin base, well in advance of anal-fin origin; dorsal adipose fin present in most, ventral adipose fin before anal fin present in many; chin barbel present, with terminal bulb in some; ventral rows of photophores, body with patches of luminous tissue, mouth large teeth elongate. Reach about 30 cm. Oviparous, eggs unknown. Larvae rare and highly diverse; elongate, gut trailing, pigment variable, dorsal fin positioned anteriorly, in advance of anal fin, eyes not stalked.

Subfamily Stomiinae (Scaly Dragonfishes): Body elongate, slender, compressed,; mouth with large, teeth large, fang-like, chin barbel prominent; dorsal fin placed far posterior, above anal-fin base, adipose fin absent; body with 5-6 longitudinal rows of scales, each with a hexagonal pigment pattern and a small photophore; postorbital photophore below eye, two longitudinal photophore rows ventrolaterally on body, small photophores on branchiostegals. Reach about 41 cm. Oviparous, eggs and larvae pelagic; larvae similar to those of Chauliodontinae, but with shorter preanus length, head relatively small, longer snout, early developing finrays and heavier body pigment.

Subfamily Chauliodontinae (Viperfishes): Body elongate, slender, compressed, covered with a gelatinous membrane; unique among stomiiforms in having a short-based dorsal fin just behind head, well before pelvic fins; first dorsal ray greatly elongate, tipped with small flap; premaxilla and lower jaw with huge fang-like teeth; chin barbel short if present; dorsal adipose far back on body, ventral adipose fin before anal fin. Body with five longitudinal rows of large deciduous scales, each with a hexagonal pigment pattern and a small photophore; large photophores in two ventrolateral rows with irregular rows of smaller photophores; branchiostegal membranes with photophores, pre- and postorbital photophore present. Reach 30 cm. Oviparous with large, round planktonic eggs; larvae elongate, yolk-sac elongate, gut almost as long as body, head short, snout pointed, eyes oval; with little or no pigment and somewhat flaccid bodies, fin rays develop slowly and larvae transform at a large size.

Subfamily Melanostomiinae (Scaleless Black Dragonfishes): Largest subfamily, body long, slightly compressed, head short, jaws large, chin barbel present; dorsal and anal fins placed far posteriorly near caudal peduncle; skin naked with minute photophores scattered over head and body, especially in vertical rows between myomeres; photophores in two ventral rows along body. Reach more than 50 cm. Oviparous with pelagic eggs; larvae diverse, many elongate with voluminous finfolds and trailing guts; head large, snout pointed, eye small, sometimes telescopic; dorsal and anal fins far back on body; larval pigment in series.

Subfamily Idiacanthinae (Black Dragonfishes): Body extremely long, slender body, almost eel-like, sexually dimorphic; dorsal-fin extremely long, anal fin about half body length, both bases ending just before caudal fin, base of each dorsal- and anal-fin ray with a spur on each side; pectoral fin absent in adults; lateral and ventral rows of photophores; minute photophores scattered over head and body; postorbital photophore sexually dimorphic; chin barbel absent in males, which retain some larval characteristics. Reach 48 cm. Larvae distinctive, very long, slender; early stages with prominently stalked eyes allowing for increased field of vision, eye stalks reaching up to one-third body length. Advanced larvae sexually dimorphic, males much smaller than females, lacking teeth, chin barbel, a functional gut and pelvic fins.

Subfamily Malacosteinae (Loosejaws): Body elongate, head large, eye large, head and snout profile rounded; mouth enormous, jaws elongate, reaching beyond skull; jaws lack membrane in floor of mouth, allowing jaws to expand widely during feeding; lower jaw connected to branchiostegals and retracted by thin band of muscle attached to tip of lower jaw; first few vertebrae unossified allowing head to swing vertically and very large prey items to be swallowed; dorsal-fin origin far behind pelvic fin, over anal fin; adipose fin and scales absent; chin barbel in most; pectoral fins absent in some; anterior and postorbital photophores present. Reach 24 cm. Oviparous, eggs unknown, larvae rare, elongate, slender, head depressed, snout elongate, eye small, jaws large; gut slender, trailing well beyond body, usually pigmented.

Food and feeding: Feeding diversity is fairly high within this group with some species specializing on fish and others on shrimp. Generally these animals feed on whatever they can fit in their mouths. Prey items can be very large in relation to body size. The viperfish, for instance, has a hinging jaw which is used to increase the gape and allow passage of large fishes. Usually midwater fishes and crustaceans

Fisheries: No fisheries, but some are frequently taken by commercial trawlers on the continental slope when the nets are lowered or brought back to the surface through deep pelagic waters.

Remarks: Males of Idiacanthus are extremely sexually dimorphic and remain very small following transformation from the larval stage, reaching about one-sixth the size of adult females. They retain many larval features and their purpose is presumably for reproduction.

Australian species:

References:

Fink, W.L. 1985. Phylogenetic interrelationships of the stomiid fishes. (Teleostei: Stomiiformes). Misc. Publ. Mus. Zool., Univ. Michigan. 171: 1-127.

Gibbs, R.H. 1964. Family Idiacanthidae, pp. 512-522. In Fishes of the western North Atlantic. Mem. Sears Found. Mar. Res. Mem. 1(4).

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.

Kawaguchi, K. & H.G. Moser. 1984. Stomiatoidea: Development, p. 169-181. In Ontogeny and Systematics of Fishes. Am. Soc. Ichthyol. Herpetol. Spec. Publ. No. 1, 760 pp.

Morrow, J.E. & R.H. Gibbs. 1984. Family Melanostomiatidae, pp. 351-51, In Olsen, Y.H. (ed.) Fishes of the western North Atlantic. Mem. Sears Fndn. Mar. Res. 1(4): 599 pp.

Moser, H.G. 1996. Melanostomiidae: Scaleless dragonfishes. In Moser, H.G. (ed.), The early stages of fishes in the California Current region, p. 308-319. CalCOFI Atlas 33. Allen Press, Lawrence, KS, 1505 pp.

Novikova, N.S. 1967. Idiacanthids of the Indian and Pacific Oceans (Pisces: Idiacanthidae). Trudy Inst. Okeanol. Akad. Nauk. S.S.S.R. 84: 159-208.

Parin, N.V. & O.D. Borodulina. 2002. Preliminary review of Astronesthes niger species group (Astronesthidae, Stomiiformes) with description of six new species from the Atlantic and Indian Oceans. Voprosy Ikhtiol. 42(4): 437-458. [In Russian. English transl. in J. Ichthyol. 42(7): 495-515.]

Parin, N.V. & O.D. Borodulina. 2003. Phylogeny, systematics, and zoogeography of the mesopelagic genus Astronesthes (Astronesthidae, Stomiiformes). Voprosy Ikhtiol. 43(5): 581-601. [In Russian. English transl. in J. Ichthyol. 43(8): 557-576.]

Parin, N.V., O.D. Borodulina & P.A. Hulley. 1999. Review of the Astronestes boulengeri species group (Astronesthidae, Stomiiformes), with description of two new species. Voprosy Ikhtiol. 39(5): 581-594. [In Russian. English transl. in J. Ichthyol. 39(8): 557-570.]

Parin, N.V. & N.S. Novikova. 1974. Taxonomy of viperfishes (Chauliodontidae, Osteichthyes) and their distribution in the world ocean. Trudy Inst. Okeanol. Akad. Nauk S.S.S.R. 96: 255-315. [In Russian, English summ.]

Richards, W.J. 2006. Ch. 19 Stomioidea: Advanced Stomiiforms; Ch. 20 Chauliodontidae: Viperfishes; Ch. 21 Stomiidae: Scaly dragonfishes; Ch. 22 Astronesthidae: Snaggletooths; Ch. 23 Melanostomiidae: Scaleless dragonfishes; Ch. 24 Malacosteidae: Loosejaws; Ch. 25 Idiacanthidae: Black dragonfishes, pp. 267-294. In Richards, W.J. 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. 1967. The osteology and relationships of the Astronesthidae, a family of oceanic fishes. Dana Rept. 71: 1-54.