Scopelarchidae
by R. K. Johnson
Midwater fishes, moderately large, more or less elongate. Eyes large, tubular, directed upward and in some also slightly forward; two sclerotic bony plates strengthen each eye; a lens pad on side of eye tube. Maxilla excluded from gape; premaxillary teeth small, retrorse, uniserial; dentary teeth biserial, the inner (medial) large and caniniform; palatine teeth in one or two irregular rows, the anterior and medial large and caniniform. Basihyal well ossified, moderately short to quite elongate, bearing large, strongly hooked teeth which decrease in length but increase in curvature from anterior to posterior portions of series; basibranchial teeth present or absent. Normal gillrakers absent, replaced by gill teeth fixed on bony plates. Branchiostegal rays 8 (4 + 4). All fins with soft rays only; dorsal fin with 5-10 rays; adipose dorsal fin present; pelvic fin abdominal, with 9 rays. Scales cycloid, covering completely body and post-orbital region. Lateral line scales large, consisting of a bony plate pierced by a central, large pore, the latter partly to completely covered by a bony shelf (tympanum) attached behind it. Luminous tissue sometimes present. Swimbladder absent.
Oceanic and meso- or bathypelagic. Adults chiefly taken between 500 and 1,000 m, larvae of most species chiefly taken within the upper 100 m, often in the upper 50 m. The principal prey appear to be other midwater fishes; despite the presence of an elongate, heavily muscled stomach, scopelarchids seem to be unable to engorge very large prey. Synchronous hermaphrodites with a functional ovotestis. Metamorphosis Fadual in most species, adult characters acquired over a size range of about 15 to 50 mm SL; larvae with 0, 1 or 3 discrete peritoneal pigment sections.
Genera 4, in Clofnam area 3.
Recent revisions: Johnson (1974).