Mutualistic Zooxanthellae

Due to living in a nutrient poor environment, many corals have a mutualistic, or symbiotic relationship. This type of relationship means both organisms are helpful for the others. These symbiotic microscopic algae are called Zooxanthellae (2). The Zooxanthellae live in the tissue of corals and assist corals in nutrient production through its photosynthetic activities, while the coral provides the algae with protection (1). This symbiotic relationship allows the coral to recieve nutrients by day, Zooxanthellae photosynthesis, and by night, through its normal sifting of the ocean water (2). Over 85 per cent of the coral's energy comes from the Zooxanthellae algae (2). The Zooanthellae also provide the corals with their color. Due to certain changes, the corals lose their symbiotic partners they change to a clear white color, which is called coral reef bleaching(2).

Picture of Microscopic Zooxanthellae --> note the green coloration, this is due to the chlorophyll (photosynthetic machines)
Picture retrieved from


Zooxanthellae are single celled algae that live in the tissues of other organisms. They usually form mutualistic relationships with these other organisms providing them with nutrients through photosynthetic properties.
Other organisms that use zooxanthellae for mutualistic properties: