Small flexible tube extending and retracting with the action of the ampulla; it mainly allows the organism to move about, anchor itself to a support and capture its prey.
central disk
Central region of the body; the starfish’s arms are attached to it.
spine
More or less movable outgrowths of calcareous plates forming the skeleton and enabling the starfish to ward off its predators.
eyespot
Small light-sensitive structure located at the terminal end of each arm, allowing it to locate surfaces and prey.
madreporite
Porous dorsal plate that allows water to enter the body; it connects the ambulacral ossicle to the outside world, and thus ensures locomotion.
arm
Movable appendage radiating around the central disk; it has a mainly tactile and olfactory function. The starfish can regenerate an amputated arm.
