THAUMATICHTHYIDAE

Females of the Thaumatichthyidae are distinguished by having an elongate body; esca bearing 1–3 large toothlike denticles (bony hooks); upper jaw extending forward far beyond the lower jaw; premaxillae bearing numerous hooked teeth; upper arm of opercle divided into two or more branches; males and larvae of Lasiognathus are unknown, metamorphosed males of Thaumatichthys are unusually slender and elongate, apparently never parasitic on females (Pietsch, 2009).