User:Schwingp/Scotoplanes

Locomotion[edit]

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. These appendages are different from the normal tube feet of the broader order of Elasipodida due the replacement of ampullae with dermal cavities to account for the larger size of the Elpidiidae tube fee. Scotoplanes move through the top layer of seafloor sediment and disrupt both the surface and the resident infauna as it feeds. This type of movement is thought to be an adaptation to life on the soft floor of the deep-sea. These creatures, however, are able to swim when disturbed. Some species of Scotoplanes are benthopelagic and spend plenty of time in the water column. A frontal lobe as well as two anal lobes propel the sea pig through the water. Their tentacles help detect their surroundings while moving.

Ventral view of Scotoplanes globosa showcasing its tube feet

Physiology[edit]

Scotoplanes are tiny and have their own defense mechanism to protect themselves from predators. Their skin contains a toxic chemical called holothurin which is poisonous to other creatures. They have external appendages which include tube feet, dorsal papillae, and buccal tentacles.

Like all echinoderms, Scotoplanes have a poorly developed respiratory system and they breathe from their anus. This refers to the lack of a respiratory tree. The body walls of Scotoplanes' tube feet are an important gas exchange location for holothuroids like Scotoplanes without a respiratory tree. Their bodies are made for the deep seas and bringing them too close to the surface would cause them to disintegrate. Also similar to other echinoderms is Scotoplanes nervous system, which consists of a network of nerves without ganglia.

Scotoplanes have unique reproductive systems that consist of one gonad in both female and male organisms. This means one ovary in females and one testis in males. This is different to 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.'

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 are responsible for the efficacy of the vascular system.

Size and Structure[edit]

Scotoplanes can be as big as up to 4-6" (15 cm) long. Scotoplanes 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.