The vital role of sea otters in maintaining a food web. Life processes - Living things in their environments - Food webs Learning Points Omnivores eat both plants and other animals. An organism can belong to several food chains. A keystone organism helps maintain the balance in their food chain. Removing one part of a food chain affects all organisms in it. A Twig Context Film. Reinforce and extend the learning required by the curriculum. Twig’s context films show abstract concepts in action in the real world.