Photosynthesis, the process by which light is converted into chemical energy is usually thought to only take place in the realm of plants and algae, but some animals also make use of this life sustaining mechanism.
Mandarins are considered difficult to keep in captivity because of their specific feeding habits. In the wild they will continuously feed during the day, pecking at prey found on the substrate in their territory, which consists mainly of copepods.
So you know that copepods make a healthy meal for the inhabitants of your reef, but what else do they do? It turns out that copepods are more important to the planet than you might think, and have more use to people beyond their inclusion in aquariums.