Hypothesis of feeding attraction for the sea star Acanthaster planci. The crown-of-thorns sea star A. planci turns its stomach out over the surface of the coral and secretes enzymes onto the living polyps. Arachidonic acid released from glycerophospholipid in coral tissue by PLA2 of A. planci may attract more sea stars. The dead coral fed on by A. planci is shown by an arrow, and the living coral is indicated by a dotted arrow.