Zooxanthellae

Zooxanthellae are tiny, single-celled creatures that live inside many sea animals, such as corals, jellyfish, and sponges. These little organisms can make their own food using sunlight in a process called photosynthesis. Because of this, they have a friendly relationship with the animals—they give them food and, in return, get a safe place to live with plenty of light.

Most zooxanthellae belong to a group called dinoflagellates, especially those in the genus Symbiodinium. They have special green and yellow colors because of the chemicals they contain, like chlorophyll and peridinin. These colors often give the host animals their bright or brown shades. During the day, zooxanthellae use sunlight to make food, which helps their host animals grow and stay healthy. This partnership helps both the tiny organisms and their animal homes thrive in the ocean.

Zooxanthellae live inside corals and help them stay healthy by giving them food. But if the water gets too warm, the coral may lose its zooxanthellae, which can make the coral turn white. This is called coral bleaching. Scientists work hard to protect these tiny creatures and the beautiful sea animals they help.