Sea urchins play a crucial role in the ocean, acting as ecosystem engineers much like large grazers on land. As they feed on seaweed and seagrass, they trim back algae and help protect slow-growing species such as corals and certain calcifying algae. In turn, sea urchins are an important food source for many marine mammals, fish, crustaceans, and sea stars. When sea urchin populations grow too large, however, especially if their natural predators are heavily hunted or overfished, the balance can flip. In these cases, intense grazing by urchins can…
