Hyperotreti (order) en

Order of eel-shaped, scaleless, soft-skinned aquatic primitive vertebrates with paired thick barbels on the end of the snout, a tail fin (but no paired fins), no jaws, cartilaginous skeletons, mouths comprising round or slit-like sucking openings with horny teeth, poorly developed eyes buried under the skin, a single nostril at the end of the snout, and five to 15 pairs of gills used for respiration. They are found in cold seawater, habitually lie buried except for the tip of the head on soft bottoms and in burrows.