|
Leftvents are small, deep-sea lophiiform fish comprising the family Linophrynidae distributed throughout tropical to subtropical waters of all oceans. The name of the type genus ''Linophryne'' has been translated from the Greek to mean "toad that fishes with a net", an allusion to the fishes' impressive use of mimicry in luring prey. One of several families of anglerfishes, the Linophrynidae are not well studied, and only one species is given a common name: the netdevil, ''Borophryne apogon''. For this reason, the name "netdevil" can sometimes refer to any linophrynid. == Description == With roughly spherical to slightly elongated, gelatinous, and scaleless bodies and large triangular heads, leftvents possess a body plan typical of deep-sea anglerfish. In females only, long, sharp fang-like teeth line the jaws of a cavernous maw. An illicium (a modified dorsal spine; the "fishing rod") — and an esca (a bulbous, bioluminescent "fishing lure") are present, also in females only. The illicium is shorter and the esca larger and complex compared to those found in some other anglerfish families, and its conformation is unique to each species. Most distinctively, ''Linophryne'' (the most diverse genus) and ''Borophryne'' species also possess greatly elongated and highly complex hyoid (chin) barbels: these barbels are forked (with three to five main branches) and may be longer than the standard length of the fish, trailing below it in a tree-like manner. Sessile bioluminescent organs are also present on the branches of this barbel. The complexity and length of the hyoid barbel varies widely among species, with some having no forkings. In ''Haplophryne'', barbels are absent altogether, and the illicium is reduced to a rounded flap. Symbiotic bacteria belonging to the family Vibrionaceae are responsible for the luminescence; the strain of bacteria is apparently different in each species. The bacteria are believed to originate from the surrounding seawater and colonise the organs via external ducts. The light produced is bluish to greenish, and the host female presumably has some control over its production. Like other deep-sea anglers, leftvents have watery flesh and poorly ossified bones; the skin, which in females is a dark brown to black in life (but colourless in ''Haplophryne''), is extremely fragile and abrades with ease. Males are more or less colourless. Females possess strong sphenotic and preopercle spines and highly distensible stomachs. Males, other than lacking lures, barbels, and (in most species) jaw teeth, have larger olfactory organs and tubular eyes; short and stout denticular teeth are also present. Sexual dimorphism is extreme: females may reach a length of , while males remain under . The pelvic fins and pelvic bone are absent in both sexes; the present fins are small and rounded. The dorsal fin and anal fin are of roughly equal size, both positioned far back from the head, and retrorse. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「leftvent」の詳細全文を読む スポンサード リンク
|