* "Hard plant" is a bit vague. It's not a recognized term in biology. Do you mean plants with tough stems, fibrous leaves, or maybe plants with thorns or other defenses?
* Herbivores are the general term. Herbivores are animals that primarily eat plants. They are a diverse group and include a wide range of feeding strategies.
Here are some specific terms that might be useful:
* Grazers: These animals eat mostly grasses and other herbaceous plants. They have adapted teeth and digestive systems for breaking down tough grasses. Examples: cows, zebras, horses.
* Browsers: These animals eat leaves, twigs, and bark from trees and shrubs. They often have smaller teeth and a different digestive system than grazers. Examples: giraffes, deer, goats.
* Frugivores: These animals specialize in eating fruits. They have teeth and digestive systems adapted to process fruit. Examples: monkeys, birds, bats.
* Granivores: These animals eat seeds. They have adaptations for cracking seeds or extracting the nutritious parts. Examples: squirrels, birds, rodents.
* Folivores: These animals eat leaves. Examples: caterpillars, some insects.
To give you a more precise answer, tell me:
* What specific type of plants are you interested in?
* What adaptations do you want to focus on?
For example, you could ask: "What are the animals that are adapted to eat tough, fibrous plants like bamboo?"