Ecology
Ecology is the study of organisms and how they interact with their surroundings whether they be abiotic or biotic. Abiotic is non-living factors (such as the wind, water, light, etc.) while the biotic factors are living things (such as parasites, predators, prey, etc.). Food-webs and food-chains are used to represent the flow of energy from organism to organism within an ecosystem.
Food Web
This is a food web. The arrows represent the flow of energy from organisms. So the snakes get energy from the toads and the toads get energy from the predaceous insects. The ultimate source of all energy from all food chains is the sun. The sun provides the energy that plants need for photosynthesis to occur. This means that the energy created from the plants is stored and used and the primary consumers will get what leftover energy there is.