You might think of a coral reef as a structure like a rock, but a coral reef is actually alive. Coral reefs are made up of a many different animals and plants (called algae). Corals are actually tiny animals called polyps that belong to the same group as sea anemones and jellyfish. Coral reels are made up of thousands of these polyps living and working together to build the reef.
The coral reef is a very colorful place. Brightly colored reef fish dart about, feeding on coral polyps, algae, and invertenrates. Sponges, anemones, and corals will amaze you with vibrant colors and unusual shapes. On a coral reef, these different colors are possible because reef-building corals have a very unique mutualistic relationship with single-celled algae (marine plants) that live within their tissues. These algae, called zooxanthellae, not only give the corals their beautiful colors, but also help them to build the reef. Mutualistic relationships like symbiosis are very common on the coral reef.
Coral reefs have very specific needs for growth and survival. As a result, they are only found in certain parts of the world, near the equator where the water is clear, warm, and shallow. Clear water is important because just like plants, the zooxanthellae must get enough light for photosynthesis to take place.
The coral reef is also a habitat. It provides a surface for algae, marine plants, and other animals to attach themselves and cement the reef together. The reef also provides crevices, caves, and hiding places for the animals that live in and on the reef. Thousands of marine plants and animals are supported by the coral reef. They hide, hunt, feed and reproduce using resources from the reef.
All the different animals that live on a coral reef make it a very diverse Habitat. That’s why sometimes, the coral reef is called the “rain forest of the sea”.