A food chain only shows ONE representative from the various levels-e.g.Leaf--> caterpillar-->bird -->cat.
The food web reflects MORE representatives from each level and THEIR interrelations e.g.leaf-->grass hopper/c'pillar/other insects --->fish/bird(here these 2 can eat each other as well!)-->cat/man.
Try putting the arrows downwards and individually for each member.This "spread-out" constitutes the web.
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