Their tail fins are rounded and truncated, and their pectoral fins are enlarged and scaleless. They have translucent, scaleless bodies reminiscent of eels. Pike congers have cylindrical bodies, scaleless skin, narrow heads with large eyes, and strong teeth. The body is scaleless and the skin is covered with easily abraded, silvery guanine. One small dorsal fin is close to the sharply pointed, mostly scaleless head. The skin of "R. glesne" is scaleless but covered with tubercles. "Grammatostomias flagellibarba" (scaleless dragonfish) are native to these waters. The fish's fins and tail are long and thin, with a scaleless body. For the scaleless and unprotected frogfish, camouflage is an important defense against predators. They are distinguished from other whalefishes by their loose, scaleless skin and lack of photophores. The body is flat on the ventral surface and naked (scaleless). The skin is thin and scaleless; the coloration is black. The skin is scaleless and smooth, in many species ornamented with varied and bright colours. The illicium and esca are contained within an illicial cavity covered in a scaleless skin. Although scaled, some filefish have such small scales as to appear scaleless.