[4][5] Worm pearlfish lack the pectoral or pelvic fins that are common characters of the family Carapidae.

The maxillaries and premaxillaries in worm pearlfishes are joined by short connective fibers in the small mouth opening.

[7] Teeth are arranged in a cardiform (comb-like) design – Parmentier suggests they are used in a saw-like fashion to cut into internal tissues of their hosts.

They seek out shallow-water sea cucumbers around in inshore waters and coral reefs which range in depth from 0-30 meters.

[5][8] They can be found in the Indo-Pacific, the Gulf of Aden, around the Philippines and Society Islands, and north to the Ryukyus to the eastern Pacific.

Species recorded as hosting the worm pearlfish include Holothuria leucospilota, H. scabra, H. lubrica and Thelenota ananas.