Food Chain: A food chain is a hierarchical series of organisms that each depend on the next as a source of food. The steps of a food chain always starts with the Sun. Then the Sun gives energy to a green plant. Then comes a herbivore [or an omnivore] who eats the green plant to get the energy. Then a carnivore eats the herbivore and gets the energy.   Harlequin ducks are carnivorous predators. They would be the last step in a 4 step food chain. In a 5 step food chain it would be prey to more vicious carnivores such as red foxes and gray wolves.

This is an example of a food chain. As you can see the harlequin duck is the superior organism in this food chain. The energy first comes from the sun, then goes to the green plant [the flowers], then to the omnivore/herbivore [the black fly], then to the carnivore [the harlequin duck].

Food Web: A system of interlocking and independent food chains. A food web starts with a green plant. It then goes to a herbivore/omnivore. It shows several different animals that eat the plants. Then it shows carnivores who eat smaller things like insects and rodents. Then finally it shows the vicious predators that will eat just about anything it can catch.  It goes from green plants [at the bottom] to fierce carnivores [at the top]. A line connects each animal to its prey. A harlequin duck is an insect eating carnivore. While it is still pretty high on a food web it is not the most vicious carnivore. It is prey to foxes and wolves and a predator to insects.

This is a example of a food web. As you can see the harlequin duck in between the top carnivores and herbivores.