Organisms of an ecosystem are linked together in

Organisms of an ecosystem are linked together in Food chains.
A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), detritivores (like earthworms or woodlice), or decomposer species (such as fungi or bacteria).
A food chain also shows how organisms are related to each other by the food they eat. Natural interconnections between food chains make it a food web.