Coral (IMAGE) Penn State Caption Corals, like the branching Acropora featured here, are animals that construct massive reef frameworks and are the basis of coral reef ecosystems. These corals ultimately depend on micro-algal symbionts that capture light from the sun and covert it to nutrients for the host coral's growth and survival. Credit Tobin T. Smith Usage Restrictions non commercial use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.