[3] Ilyophinae has a name based on that of its type genus Ilyophis, this name combines ilys which is Greek for "mud", probably an allusion to the soft, silty substrate habitat of I. brunneus, with ophis, meaning "serpent", referring to the snake-like shape of eels.

In most taxa the upper body lacks scales and in some Dysomma species as well as Thermobiotes do not have a pectoral fin.

[1] These eels show very variable body shapes, dentition, whether they possess pectoral fins, the size of the eyes and the structure of the snout.

In some species, the anus is positioned rather far forward onthe body, almost beneath the pectoral fins, if any.

[6] Ilyophinae eels are benthic species found in deeper waters in the Atlantic, Indian and Pacific Oceans.