Animal

Animal is the broad word scientists use for living creatures that are not plants, fungi, or bacteria. Animals take in oxygen, release carbon dioxide, and move on their own at least once during life, even if only as larvae. From tiny mites to giant whales, animals form the most visible part of ecosystems and rely on the same basic ingredients: energy from food, water to stay hydrated, and the right temperature range.

Animals are grouped by shared traits. Invertebrates lack backbones and include insects, worms, mollusks, and jellyfish. Vertebrates have internal skeletons, such as fish, amphibians, reptiles, birds, and mammals. These groups help scientists predict body plans, habitats, and life strategies without seeing every species firsthand.

Because animals cannot make their own food, they must eat other organisms. Herbivores graze on plants, carnivores hunt or scavenge other animals, and omnivores mix both menus. Some animals filter tiny plankton, while others use sharp teeth or strong beaks to tackle tough meals. Digestive systems match the diet: a cow's four-part stomach breaks down grass, while a snake swallows prey whole.

Survival also depends on senses and communication. Animals use eyes, ears, whiskers, antennae, and even electric fields to learn about danger or opportunity. Bees dance to point nestmates toward nectar, wolves howl to keep their pack together, and fireflies flash patterns to find mates. Many species migrate or hibernate to handle seasons that become too cold, dry, or food-poor.

People interact with animals every day. Pets share homes, farm animals provide eggs, milk, and fiber, and wild animals pollinate crops, spread seeds, and control pests. Caring for habitats, reducing pollution, and respecting wildlife laws keep animal populations healthy so future generations can study and enjoy them. Zoos, aquariums, and wildlife rescue centers teach visitors about these responsibilities while protecting endangered species.