The starfish constitutes the class Asteroidea and are the most familiar echinoderms. About 90 species can be found around southern Africa.
Starfish have a flattened central body which merge imperceptibly into five or more, relatively stout, projecting arms. Each arm contains its own set of respiratory, digestive and reproductive organs.
Under each arm lie rows of delicate hydraulically-operated cylindrical tubefeet with suckered tips, which are protected within a groove running from the mouth along the underside. These tubefeet provide the main mode of locomotion, a slow creeping movement characteristic of the starfish.
The mouth is situated centrally on the under surface, while the anus is on the upper side.
Some starfish feed on detritus or microalgae, but many are predators. Among the predators, some control mussels and prevent them from monopolizing the shore.
The crow-of-thorns starfish (Acanthaster planci) is infamous for the devastating effects it can have on corals.
F*CK FISH 