Echinodermata
Echinodermata are aquatic organisms that are best recognizable by their five point symmetry (like starfish). They can be found at every ocean depth and are made up of 7000 species. Echinoderms are the largest phylum with no terrestrial representatives. They date back to the Cambrian period and are well known for their remarkable ability to regenerate lost tissues and limbs at rapid paces.
The excretory system of enchinoderms
Echinoderms have an extremely primitive excretory system. Wastes are simply diffused through the skin of the organism or excreted as feces at the end of digestion.
Examples
Starfish (Asteroidea), like other echinoderms have very basic excretory systems. Most wastes are excreted through the diffusion of nitrogen gas or the excretion of feces at the end of digestion from the anus.
Sea urchins (Echinoidea) release their wastes by the excretion of feces as well as the release of liquid from pores all over its body.
Crinoids (Crinoidea) excrete their wastes by both diffusion through the skin and also the excretion of feces.