Though they do feed on other organisms, most of corals 'nutritional needs are provided by the Symbiodinium algae that reside amongst them. These algae use the carbon dioxide that coral exhales, water, and sunlight to photosynthesize nutrients that coral uses. The coral returns the favor by producing the ammonia, phosphorous, and carbon dioxide that the algae require for survival.
居住在珊瑚組織中的共生藻，利用珊瑚呼吸產生的二氧化碳、水和陽光進行光合作用，提供珊瑚所需養分，珊瑚也禮尚往來地提供共生藻生存所需的氨、磷、二氧化碳。