Scotoplanes grow to in length. They are
bilaterally symmetrical with six pairs of
tube feet, which are largest at mid-body and smallest near the
anus.
Scotoplanes also have ten
buccal tentacles lining the
oral cavity.
Papillae are found on their dorsum ("back"). They also possess a
defence mechanism to protect themselves from predators; their skin contains a toxic chemical called
holothurin, which is poisonous to other creatures. Like all
echinoderms,
Scotoplanes have a poorly developed respiratory system and breathe from their anus, referring to the lack of a
respiratory tree. Their bodies are adapted to the high pressure of the
benthic zone of the ocean, and bringing them too close to the surface would cause them to disintegrate. Similar to other echinoderms,
Scotoplanes have a
water vascular system. The dorsal papillae are similar
histologically to
Scotoplanes tube feet, as both contain a large muscular water vascular canal in the center. Hydraulic pressure in these canals is responsible for the efficacy of the vascular system. Also similar to other echinoderms is
Scotoplanes 's nervous system, which consists of a network of nerves without ganglia. A study done provides histologic findings that these deep-sea dwelling sea pigs are similar to other
holothuroidea. However, there are a few notable differences: most holothurians are sexually
dioecious with sexes in separate individuals. Unlike other echinoderms, holothuroids possess only a single gonad. The water vascular system of holothurians is similar to other echinoderms, except the madreporite opens in the perivisceral coelom instead of in the external body wall.
Scotoplanes have unique reproductive systems that consist of one gonad in both female and male organisms; one ovary in females and one testis in males. This is different from most
echinoderms. 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, they feed on organic matter that falls to the bottom of the sea, gathering and ingesting this detritus with their tube feet. Their gut is highly efficient, allowing the maximum amount of nutrition to be extracted from meager resources available in the animal's immediate environment. Male
Scotoplanes have
protozoa inside the cyst cavities of their aboral intestines. These appendages are different from the normal tube feet of the broader order of Elasipodida due to the replacement of ampullae with dermal cavities to account for the larger size of the Elpidiidae tube feet.
Scotoplanes move through the top layer of seafloor sediment and disrupt both the surface and the resident
infauna as they feed. This type of movement is thought to be an adaptation to life on the soft floor of the deep sea. These creatures, however, can swim when disturbed. Some species of
Scotoplanes are benthopelagic and spend plenty of time in the water column. The frontal lobe as well as two anal lobes propel the sea pig through the water. Their tentacles help detect their surroundings while moving. == Ecology ==