Reefs can be home to algae, fish, and many kinds of invertebrate marine life, all sharing and creating the reef ecosystem.
All of the creatures living within a reef are dependent upon it and one another for survival. The reef interacts with these creatures on several levels.
Polyps in a coral reef have a symbiotic relationship with photosynthetic organisms called zooxanthellae, which supply their hosts with carbon.
Polyps can also trap zooplankton from the water to help supply themselves with energy and nutrients.
Sponges and other invertebrates fill over 60 percent of reef cavities, and contribute to the nutrient cycle in the greater reef ecosystem by filtering the water and excreting inorganic nutrients.
Fish are at the top of the food chain in coral reefs, with different varieties of fish deriving nourishment from different sources, such as algae, invertebrates, smaller fish, or even the reef polyps themselves.
