4, 2, 1, and 3 is the answer
Answer: Seastars prey on mussels and shellfish which would otherwise have no other natural predators. Herbivorous fish like the butterflyfish pictured to the left prey on marine algae. Without this crucial predator-prey balance, the algae would over-grow, which would then kill coral, as they compete for the same resources.
I think is true i took the test but im not sure what i put! Correct me if wrong