It is up to 50 cm (20 in) long but just 5 mm (0.2 in) wide, with a rounded head slightly broader than the body.

Specimens preserved in alcohol lose their colour but exhibit a transverse dark band.

[3] This worm can be distinguished from other similar species by the absence of whitish bands or stripes on the body or white patches on the head,[2] as well as by certain muscle fibres crossing over muscle layers in the dorsal part of the body wall, but not in the ventral part.

The females lay eggs which are fertilised externally and develop directly into juvenile worms.

It is possible that its bright red colouration is aposemetic, giving warning that this particular ribbon worm is toxic or unpalatable.