Carnivores eat animals. Parasites reside in or on living hosts and extract energy from them. Omnivores eat a variety of organisms. Decomposers are also heterotrophs and include fungi and bacteria that extract energy from the remains or products of organisms. An ecosystem is a complex of organisms interacting with one another and with the physical environment.
Ecosystems are open systems through which energy flows and materials are cycled.
B. Structure of Ecosystems 1. Decomposers feed on organisms from all levels. Interconnected food chains comprise food webs in which the same food resource is often part of more than one food chain. A. Primary Productivity 1. Primary productivity is the rate of photosynthesis for the ecosystem during a specified interval.