Food webs are simplifications of a much larger ecosystem and its interactions. Above are three food webs containing basic species from each third (upper, middle, and lower portions respectively) of the Wicomico River. All the species in these food webs are native to the Wicomico River and can still be seen there today. Because the salinity of the water changes throughout the river, so do the species able to live there. All of these food webs overlap and contain many more species than shown. These basic examples are useful for visualization.
All food webs start with the sun. The sun gives plants energy to grow, which means they are autotrophs. Anything that creates its own energy is an autotroph. Animals, because they eat other species to obtain their energy, are called heterotrophs. Click the images for more about that food web and the species included. Follow the black arrows that represent the flow of energy to see how species survive and interact. Blue arrows point to species that directly provide habitats for another animal in the web. Below is a food web that depicts how the invasive species, nutria, affects the middle portion of the Wicomico River. Species that nutria directly removes are crossed out, and the gray arrows show how other parts of the food web suffer.