Image courtesy of the Thomas Burke Memorial Washington State Museum

Herbivores often become prey.  Instead of having eyes in the back of their head, they have eyes placed on the sides of their heads, allowing them to see almost all the way around their bodies. In this way, they can keep a constant watch for predators, so they can run if they sense danger. Have you ever watched deer eating grass in a field? They will browse with their heads near the ground, but every so often, they will raise their heads, perk up their ears, listen and look around for predators. 

Ears for listening

Why do deer, elk, antelope, rabbits, mice, and sheep have such big ears? So they can listen for approaching predators. Large ears help to amplify (increase) sound, so they can hear if danger is nearby. Since most herbivores lack claws and/or powerful, sharp front teeth to defend themselves, they must be able to see and hear predators before they are too close.   

Omnivores eat both meat and plants, but not all kinds of plants. Unlike herbivores, omnivores cannot digest some of the substances in grains or other plants because their stomachs are not designed to do so.  For example, while we can eat fruits and vegetables,  humans do not eat wheat or other grains straight from their stalks.  We process them and then bake them into bread or other foods so our bodies can digest them.  

Teeth for meat and plants

Unless you're a vegetarian, you're an omnivore. Humans have the necessary teeth to help us rip into meat and to help us bite into fruits and vegetables.  We also have molars to help us grind up our food so we can digest it.  Other omnivores, such as bears and raccoons, will hunt for meat or scavenge meat from other predators; they also complete their diet with plants such as berries and other fruits.