The main players in my shark animation. We have a black-tip reef shark, a white tip reef shark, a nurse shark, a parrotfish, and a red grouper. What happens is the parrotfish eat the algae, the groupers eat the parrotfish, and the sharks eat the groupers. If sharks are over-fished, the groupers will devour all of the parrotfish and algae will choke the reef. And as anyone who has a swimming pool knows, algae blooms are disgusting.
