Corals may look like plants but they are in fact animals. The technical definition of a plant is an organism able to absorb inorganic substances and water through the roots and synthesise nutrients by photosynthesis using the green pigment chlorophyll. As corals are unable to produce their own food, they are classified as animals.
It can be confusing as corals are known as sessile’, meaning they permanently attach themselves to a spot on the ocean floor, similar to the way plants are rooted to the ground. They are also sometimes mistaken for rocks because the hard limestone the polyps secrete builds up over time and hardens into a rock-like structure.
They are able to survive through a symbiotic relationship with zooxanthellae, a type of algae that lives in the coral’s tissue. The algae benefits as it is well protected by the coral, and in return, the algae produces oxygen and removes waste for the coral. It then uses this waste for photosynthesis.