Corals get their food from algae living in their tissues or by capturing and digesting prey. M ost reef-building corals have a unique partnership with tiny algae called zooxanthellae. The algae live within the coral polyps, using sunlight to make sugar for energy.This energy is transferred to the polyp, providing much needed nourishment. In turn, coral polyps provide the algae with carbon dioxide and a protective home. Corals also eat by catching tiny floating animals called zooplankton.At night, coral polyps come out of their skeletons to feed, stretching their long, stinging tentacles to capture critters that are floating by.he algae live within the coral polyps, using sunlight to make sugar for energy. This energy is transferred to the polyp, providing much needed nourishment. In turn, coral polyps provide the algae with carbon dioxide and a protective home.