Communication and Perception
The non-centralized nervous system allows echinoderms to sense their environment from all sides. Sensory cells on the epidermis sense light, contact, chemicals and water currents. Higher densities of sensory cells are found in the tube feet and along feeding canal margins.
Red pigmented eye spots are found on the end of each arm. These function as photoreceptors and are clusters of pigment-cup occelli.
Adult pheromones may attract larvae, which tend to settle near conspecific adults. Metamorphosis in some species is triggered by adult pheromones. (Brusca and Brusca, 2003; Canada's Aquatic Environments, 2002)