Echinoderms run a water vascular system: a network of internal canals filled with seawater, connected to podia at the surface. Raising the pressure in a canal extends a tube foot; releasing it lets the foot shorten. In Scotoplanes several pairs of these podia are greatly enlarged, so the animal stands clear of the mud and steps across it.
Walking above the sediment matters at abyssal depths, where the food is a thin layer of freshly settled organic particles at the surface of very soft mud. Sea pigs detect and congregate on these deposits, and dense aggregations are commonly recorded around falls of organic material.
The animal is not a mammal and is not related to pigs beyond a resemblance in profile. It is also frequently described as rare, which reflects the difficulty of observing the abyssal plain rather than genuine scarcity; sea pigs are among the more abundant large invertebrates on deep soft bottoms. How they locate patches of settled food across open mud is not well established.