[3] The calcareous ring and spicules of Holothuroidea are useful in determining phylogeny, as they vary greatly and are believed to have evolved independently as species adapted to various biotopes.

[3] All psychropotidae can swim short distances, yet certain species, such as Psychropotes longicauda spend much of their juvenile phase in the pelagic zone.

[5] "Mortensen, 1927, speculated that 'The long tail probably is a swimming apparatus"; his suggestion is apparently true for juveniles of this species, but not for adults".

[6] Several authors describe the ability of a number of Psychropotes species to use a large, unpaired dorsal appendage as a 'sail' to move with the prevailing current, contorting their body so as to steer their movement.

The great variation of this appendage throughout the Holothuroid family suggests that this adaptation is significant in allowing species to access food sources in the food-scarce environments in which they live.