Starfish breathe through their feet. Their feet are made of thin tissue that gases can easily move through. Starfish’s tubed feet and tiny bumps all over their bodies transport the oxygen from the seawater to their tissues. They move carbon dioxide from their tissues to the seawater.
Starfish can smell food through chemicals released by their food being washed toward them in currents. The starfish have chemical reception structures that allow them to do this. Starfish can regenerate limbs, but most of the central disc must remain to do this. Single arms usually die, unless they are from the Linckia species, which can regenerate a new individual from one arm. They can split themselves in half and form two new bodies when they feel they need to increase their population size through asexual reproduction.
Starfish eat bivalves by using their tubed feet to pry a gap into the bivalve's shell and moving their stomach through their mouth opening and into the shell. Starfish then use their digestive liquids to liquefy the animal inside the shell and suck it in. Starfish do not have ears or image-forming eyes, but they have eyespots on the end of each arm. The eyespots contain a red pigment that changes in the presence of light. They also lack central brains.