ophidiiform

Ophidiiform is a traditional order of ray-finned fishes that includes cusk-eels, pearlfish, and some less common families. These fishes are typically marine, found in all oceans from shallow coastal waters to the deep sea. A common characteristic of ophidiiforms is their elongated body shape, which is often tapering towards the tail. Their dorsal and anal fins are usually long and continuous with the caudal fin, giving them a snake-like appearance, hence the name derived from the Greek word "ophis" meaning snake. Many species possess a small chin barbel, which is a sensory appendage used to detect prey in low-light conditions.

Ophidiiforms exhibit a wide range of ecological roles. Some are benthic, living on the seafloor, while others are pelagic, inhabiting the open water column. Their diet varies, including crustaceans, mollusks, polychaetes, and smaller fish. Reproduction in this order is diverse, with some species being oviparous (egg-laying) and others viviparous (live-bearing). While some species are commercially important, many ophidiiforms are not well-studied due to their deep-sea habitats. Recent molecular and morphological studies have led to a reclassification of this group, with some families formerly placed within Ophidiiformes now being assigned to separate orders. However, the term "ophidiiform" is still widely recognized and used to refer to this assemblage of fishes.