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Movement:
They possess a hydrostatic skeleton consisting of the coelom and surrounding muscles.  It uses the combination of its longitudinal body retractor muscles, which run along the ambulacra, against the inner body wall, and fluid pressure from the coeloms to change its shape.  Additionally, the body walls are muscular.  The epidermis contains many conspicuous external warts and soft spines, highly modified podia with lateral canals and reduced ampulla.​

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Digestive System:
They deposit and suspension feed using their branched buccal podia (labeled feeding tentacles in diagram).  These buccal podia are modified and enlarged tube feet.  The buccal podia deposit detritus and sediment into the esophagus that then travels down the proximal (descencing) and distal (ascending) intensine.  Surrounding the small intestine are gastric hemal vesels and the plexus complexus.  Next the sediment travels to the large intestine to the rectum, and out the anus.​

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Respiratory System:
Respiration occurs at the podia and via rectal pumping into highly branched respiratory trees, suspended within the coelom.

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Reproductive System:
The gonad is located on the dorsal side of the sea cucumber and is made of highly branched tubules.  Gametes are ejected through the gonopore, which, in P. parvimensis, is retracted within the body until spawning.​

Defense:

Under stressed conditions or when they feel threatened, sea cucumber spew out their viscera in a process called evisceration.  Their viscera consist of their gonads, circulatory, and Cuverian tubules, defensive sticky secretions.  Sea cucumbers find good hiding places while their organs regenerate.