What do corals eat?
Corals can capture prey (usually plankton) by stinging them with their tentacles and bringing the plankton inside to dine on. In addition, corals rely on the photosynthetic products of algae for their food. Inside coral tissue lives a one-celled alga called zooxanthellae. Nutrients from the algae feed the corals, allowing them to grow and reproduce. Safe inside the corals, the plantlike algae flourish in the tropical sun. The algae, like all plants, need sunshine for photosynthesis, which is why coral reefs grow so near the surface of the water, where it is sunniest. Some corals can grow as much as nine inches each year. The energy used in this growth is much greater than the eating of plankton would allow. This explains why zooxanthellaeare so important to the lives of the corals.
A coral polyp consists primarily of tentacles, a mouth and a gut (think upside down jellyfish). Many corals are passive feeders on plankton. Most corals also get nutrition from microscopic algae (zooxanthellae) living within their tissue. Coral polyps are generally nocturnal feeders and are provided sugars made by their photosynthetic zooxanthellae during the day.
