Knowra Ophidiiformes Ophidiiformes Ophidiiformes is an order of ray-finned fishes that includes cusk-eels, brotulas, and pearlfishes. Many species live near the seafloor or in the deep sea.
Cusk-eels : Cusk-eels are elongate marine fishes in the family Ophidiidae, often with pelvic fins reduced to a single barbel. They are the order’s namesake group and one of its principal families.
Pelvic fin : A paired fin located on the underside of a fish, corresponding to hindlimbs in tetrapods. In many cusk-eels, pelvic fins are reduced and joined into a sensory barbel.
Hadopelagic zone : The ocean zone below 6,000 meters, extending to the deepest trenches. A few ophidiiform fishes occur at depths that approach or enter this zone.
Abyssobrotula galatheae : A deep-sea brotula recorded from the Puerto Rico Trench at a depth exceeding 8,000 meters. It is a striking example of an ophidiiform fish reaching hadal depths.
Brotulas : Brotulas are fishes in the family Bythitidae, a group that includes marine and freshwater species. They represent a major family of Ophidiiformes beyond the cusk-eels.
Swim bladder : A gas-filled organ that helps many bony fishes control buoyancy. Its structure and function vary among deep-living ophidiiforms adapted to pressure and depth.
Abyssal plain : A broad, nearly flat region of the deep-ocean floor, generally thousands of meters below sea level. Abyssal surveys record ophidiiforms living and feeding on deep seafloor habitats.
Carapus acus : A pearlfish species that lives in association with sea cucumbers in the Mediterranean and eastern Atlantic. Its host association illustrates the specialized ecology of Carapidae.
Pearlfishes : Pearlfishes are slender fishes, mostly in the subfamily Carapinae, whose adults may live inside invertebrate hosts. Their distinctive host associations mark a specialized branch of the order.
Benthic zone : The ecological region at the bottom of a body of water, including its sediment and surface. Many members forage or shelter on the seafloor rather than in open water.
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