Sea Urchins
Sea urchins commonly referred to as sea-hedgehogs are small spiny animals that populate the bottom of the sea. Lower classifications of this animal include Euechinoidea, Perischoechinoidea, and Chondrocidaris gigantea. Sea urchins feed on many types of algae by eating it using their circular mouth located at the center of their body. Sea urchins use their hard spike to protect against predators but still sea otters are able to eat them. The nervous system of sea urchins is quite simple as they have no true brain. Rather than a brain they have a neural center which is a large nerve ring located at the ring of the mouth. branching off from the nerve ring are finer nerves that branch off to control the tube feet, spines, and pedicellariae (a small claw shaped structure).