The predator eats and the prey is eaten. Energy moves through the the ecosystem and the population is controlled, Producer - Any organism that can photosynthesize, or any organism that can use light energy, chlorophyll, water and carbon dioxide into chemical energy in the form of carbohydrates. Symbiosis - is the interdependence of two different species. There are 3 different types of symbiotic relationships. Parasitism occurs when a smaller organism lives off of a larger one and gives nothing in return.
Leeches are parasites.
Many viruses and bacteria are parasites. Because the parasite depends on its host it rarely kills it. Mutualism occurs when both organisms benefit. Such as when algae lives in the gut of a protozoan. Commensalism occurs when one organism benefits and the other is unaffected.