Where do food webs and food chains come from?

A food web is a series of lines coming from one animal to another with an arrow at the end. A food chain is a kind of chart with lines coming from one creature to another, again with arrows. the difference is that a food chain can only have one arrow pointing to each animal. if an arrow points to an animal, it means wherever the arrow is coming from, the animal goes to the animal whom the arrow is pointing to. i don't know how to answer where they come from, but i hope i helped