In Brittle stars all the five arms (with tbe feet) are attached to the central disc which contains all the body organs. The mouth, on the underside of the body, is surrounded by five jaws. The mouth also acts as the anus, food is digested in 10 pouches or infolds of the stomach pouch.
Most Brittle stars are scavengers or detrivores eating decaying matter and plankton. Some are predators, pushing their stomach out through their mouth to digest their prey. Basket stars are suspension feeders, using the mucus coating on their arms to trap plankton and bacteria. They extend one arm out and use the other four to anchor them in place.
Brittle stars have no brain, eyes or any other specialised sense organs. However, they have several types of nerve ending in their skin and can sense chemicals in the water, touch, and even the presence or absence of light.
Most Brittle stars are either males or females and fertilisation takes place in the water. In some species, the eggs develop in sack-like body cavities called bursae. In a few species the embryos are fed by nutrients which pass through the walls of the bursae.