Members of the Elpidiidae have particularly enlarged tube "feet" that have taken on a leg-like appearance, using water cavities within the skin to inflate and deflate thereby causing the appendages to move.

Scotoplanes move through the top layer of seafloor sediment and disrupt both the surface and the resident infauna as they feed.

Sea pigs are also known to host different parasitic invertebrates, including gastropods (snails) and small tanaid crustaceans.

Their digestive system is specialized, too, as detritivores, the animals feed on organic matter that falls to the bottom of the sea, gathering and ingesting this detritus with the tube feet.

Their bodies are made for the deep seas and bringing them too close to the surface would cause them to disintegrate, due to the lower pressure.

Also unique from most elasipodids is that active gametogenesis was observed in both females and males, pointing to a different reproduction strategy in Scotoplanes.

Their digestive system is specialized, too, as detritivores, the animals feed on organic matter that falls to the bottom of the sea, gathering and ingesting this detritus with the tube feet.

The dorsal papillae are similar histologically to Scotoplanes' tube feet, as both contain a large muscular water vascular canal in the center.

[14] The genus includes the following species:[15] A study done provides histologic findings that these deep-sea dwelling sea pigs are similar to other holothuroidea, though there are few notable differences: most holothurians are sexually dioecious with sexes in separate individuals.

The water vascular system of holothuians is similar to other echinoderms, except the madreporite opens in the perivisceral coelom instead of in the external body wall.