The crown-of-thorns sea star, Acanthaster planci, preys on the flesh of live coral. If coral animals are attacked by these sea stars, then what actually provides nutrition to the sea star, and which chemical (besides the toxin within their nematocysts)do the corals rely on for protection?
A) medusas; silica B) exoskeleton; silica C) exoskeleton; calcium carbonate D) polyps; calcium carbonate E) polyps; silica