The snailfish family is poorly studied and few specifics are known. Their elongated, tadpole-like bodies are similar in profile to the rattails. Their heads are large (compared to their size) with small eyes their bodies are slender to deep, tapering to very small tails. The extensive dorsal and anal fins may merge or nearly merge with the tail fin. Snailfish are scaleless with a thin, loose gelatinous skin some species, such as Acantholiparis opercularis have prickly spines, as well. Their teeth are small and simple with blunt cusps. The deep-sea species have prominent, well-developed sensory pores on the head, part of the animals' lateral line system. The pectoral fins are large and provide the snailfish with its primary means of locomotion although they are fragile. They are benthic fish with pelvic fins modified to form an adhesive disc this nearly circular disc is absent in Paraliparis and Nectoliparis species. Snailfish range in size from Paraliparis australis at 5 cm (2.0 in) to Polypera simushirae at some 77 cm (30 in) in length. The latter species may reach a weight of 11 kg (24 lb), but most species are smaller. Snailfish are of no interest to commercial fisheries.