Asteroidea
Asteroidea is the class commonly referred to as Starfish. Members of this class have no excretory organs. In order to excrete solid waste, the Starfish uses its Water Vascular System to flush out any waste substances, or expel through its anus, which is located in the center of the starfish. Nitrogenous waste is discarded through its tube feet.
Sand Dollar
Sand dollars are a disk-like order of animals. Like asteroidea, sand dollars also have no excretory organs. These organisms exclusively use the Water Vascular System to excrete. This system also facilitates many other life processes in the Sand Dollar.
Holothuroidea
Holothuroidea (Sea Cucumbers) gathers food through its tube feet. Once this food has been broken down into usable nutrients, it continues on to the pharynx, or the connecting organ between the tube feet and the intestine. The intestine then leads to the anus, where the waste is excreted.