Stomiiformes
English: Dragonfishes; Stomiiforms.
Name: from Ancient Greek stóma, mouth and Latin forma.
Members: Dragonfishes, Lightfishes, Loosejaws, Marine hatchetfishes, Viperfishes.
Genera: 50; 410 species; 4 to 5 families.
Region: subtropical and temperate waters up to subarctic or even Antarctic ones.
Habitat: deep-sea, pelagic, deep oceanic waters.
Zoology
Ray-finned fishes; almost nightmarish appearance; teeth on the premaxilla and maxilla; maxillary ligaments, as well as some muscles and certain bones in the branchial cavity, are specialized; large mouths extending back past the eye; some have a chin barbel; scales are cycloid, delicate, easily sloughed off; some are scaleless; teeth are often transparent, ue to nanoscale structures composed hydroxyapatite and collagen and a lack dentin tubules; teeth are non-reflective.
Color: dark brown or black; some are silver.
Form: very diverse morphology; huge mouth opening.
Size: 1.5 cm to 50 cm.
Fins: lacking dorsal and pectoral fins, others have an adipose fin; pelvic fin has 4 to 9 rays; 5 to 24 branchiostegal rays.
Bioluminescence: photophores are common, consisting of small gleaming points on the fish body or very elaborate, involving lenses and refractors, radiating light yellow, white, violet or red; 1 to 2 rows on the ventral aspect of the body, from the head down to the tip of the tail, some in chin barbels; produced by an enzymatic reaction, a catylization of coelenterazine by calcium ions.
Behavior: in deep waters during daytime, at night to near-surface water.
Food: small fishes and planktonic invertebrates.
Reproduction: spawn generally in deep seas; eggs are light and float towards the ocean surface, hatch in surface waters; certain members change their sex during their life, male when mature, later transformed into females.
Taxonomy
Stomiiformes are often placed in the teleost superorder Stenopterygii, together with the Ateleopodiformes, sometimes on their own. Closest relatives of the "Stenopterygii" are found among the superorder Protacanthopterygii. Some keep Stenopterygii separate or include them with the Protacanthopterygii and the monotypic superorder Cyclosquamata in an unranked clade called Euteleostei.
Stomiiformes have also been considered close relatives of the Aulopiformes. The latter are otherwise placed in a monotypic superorder "Cyclosquamata" but also appear to be quite close to the Protacanthopterygii indeed. The relationships toLampriformes or Myctophiformes is still not well resolved.
Families
Suborder Gonostomatoidei
• Gonostomatidae : Bristlemouths, Anglemouth, Lightfishes; including Diplophidae.
• Sternoptychidae: Marine hatchetfishes, Bottlelights, Constellationfishes, Pearlsides.
Suborder Phosichthyoidei
• Phosichthyidae: Lightfishes.
• Stomiidae : Barbeled dragonfishes; Loosejaws, Stareaters.