Organisms that obtain energy by eating only plants are called herbivores.

Here are some examples:

* Mammals: Cows, horses, rabbits, deer, giraffes, elephants, goats, sheep

* Birds: Chickens, parrots, ducks, geese, finches, hummingbirds

* Insects: Caterpillars, grasshoppers, butterflies, aphids

* Fish: Some species of fish, such as carp and catfish, eat algae and aquatic plants.

* Reptiles: Some species of turtles and lizards are herbivorous.

It's important to note that some organisms might be primarily herbivorous but may occasionally eat small amounts of animal matter. For example, cows will sometimes consume insects while grazing.