Respiration

In echinoderms, their respiration varies depending on the species. Mostly, they all respire by exchanging oxygen and carbon dioxide through the thin-layered tissues on their tube feet. Also they use some of the bumps and spines on the surface of their body to take in oxygen. Some echinoderms have a gill structure called skin gills that also allows for respiration. In sea cumcumbers, they take in oxygen with their respiratory trees which gets oxygen through the anus. The sea cucumbers contract and expand the muscle walls of their anus to draw in and release water in a slow rhythm. By creating this water movement, it allows the respiratory tree to take in the oxygen for breathing.