There are many different kinds of animals in the world. When scientists work to group animals, they look for things the animals have in common. For example, they might consider what an animal eats, where they live, or what they look like.
One way scientists group animals is by what an animal eats. Animals are creatures that get their energy from other living things. Some animals, called carnivores, eat other animals. Some animals get their food from eating plants. They are called herbivores. If an animal eats both animals and plants, they are known as omnivores.
Different animals have changed or adapted to different habitats. A habitat is where an animal lives. For example, fish, whales, and dolphins live in the ocean. Zebras, giraffes, and lions live in grasslands. Tigers, chimpanzees, and tree frogs live in the rainforest. The animals who live in these places have adjusted to their unique climate. Where they live also determines what they eat.
Animals may also be grouped based on their appearance. Looking at body coverings, foxes, polar bears, and rabbits might be grouped together because they all have fur. Snakes, pangolins, and goldfish all have scales. Birds are animals that have feathers. They might also be grouped based on how they move. Blue jays, butterflies, and honey bees fly. Whales, dolphins, and seals swim.
Adapted from: https://simple.wikipedia.org/wiki/Animal