Hooks: 7-9; anterior teeth: 3-7; posterior teeth: 6-16.
Maximum adult body length: 10 mm; tail: 17-21 %.
Body very small and slender, transparent, with broad tail; transversal musculature absent; head narrow; hooks not serrated. Fin bridge absent. Anterior fins of medium length, partially rayed, rounded; posterior fins of medium length, partially rayed, rounded. Collarette absent. Small gut diverticula present. Small eyes, with star-shaped pigment spot. Seminal vesicles with knob and trunk; position of seminal separated: from posterior fins, touching tail fin. Ovaries very short and broad, reaching to middle of posterior fins; ova very large but few. Adhesive papillae and adhesive organs absent. Apical glands absent.
Distribution: epipelagic; circumglobal between 40°N and 40°S.