What are three essential environmental components needed for corals to survive? Objective Students will be able to: 1. Identify the three essential environmental components needed by corals to survive. 2. Identify the physical factors that limits where coral reefs develop. Background Coral reefs are some of the most diverse ecosystems in the world. Corals (amu) are actually colonies of tiny animals living together on the reef. The individual animals that build the reef are called “coral polyps”. Within the body of the coral polyp live small, single celled algae known as “zooxanthellae.” These Duration: 60 Minutes.