[4] As an adult, Psychropotes longicauda has eighteen short feeding tentacles, each with a leathery terminal disc with retractile processes projecting around the margin.

At the posterior end there is a dorsal, tail-like appendage up to 12 cm (4.7 in) long, either pointed or with a pair of unequal-length tips.

[6] Psychropotes longicauda is a cosmopolitan abyssal species of sea cucumber and is found on the seabed throughout the world's deep oceans.

[6] Adult Psychropotes longicauda are found on soft sediments through which they sift with the aid of their feeding tentacles.

The size of the eggs, and the fact that the larvae do not appear to feed, makes it so that the yolk nourishes them for an extended time and that they can therefore disperse widely.