What Living Things Need: Food, Water, Air, and Shelter

A bear eats berries before winter. A sunflower turns its face toward the sun. A fish swims toward the part of the river with more oxygen. These three living things look very different from each other — but they are all doing the same thing. They are getting what they need to survive. Every single living thing on Earth — from the tiniest ant to the biggest whale, from a blade of grass to a giant redwood tree — needs four things to stay alive. Learn those four things, and you will understand something true about every creature that has ever lived.

In this lesson you will: • Name the four things all living things need to survive. • Explain how plants get their food, water, and air without moving around. • Describe how animals find or make shelter and find food and water. • Look at nature and spot living things meeting their needs.

All living things — plants, animals, fungi, and even tiny microbes — need these four things: 1. Food: energy to grow, move, and repair. Plants make their own food from sunlight. Animals eat plants or other animals. 2. Water: every living cell needs water to work. Without water, cells dry out and die. You need about 5-6 cups of water a day just to stay healthy. 3. Air: animals breathe oxygen from air. Plants breathe in carbon dioxide from air and breathe out oxygen. Even fish breathe — they pull dissolved oxygen from water using their gills. 4. Shelter: a safe place to rest, stay warm or cool, and raise young. A nest is shelter. A burrow in the ground is shelter. A shell is shelter. A den in a hillside is shelter.

Plants are amazing because they never have to go anywhere to find food — they make it themselves! • Water: plant roots reach down into the soil and soak up water. The water travels up through the stem to every leaf. • Sunlight: leaves are shaped like wide, flat collectors that catch as much sunlight as possible. Have you ever noticed how a plant near a window leans toward the light? It's reaching for what it needs. • Air: tiny holes in leaves — so small you need a magnifying glass to see them — let carbon dioxide in from the air. These holes are called stomata (stoh-MAH-tah). • Food: plants use sunlight, water, and carbon dioxide together to make their own food. This is called photosynthesis. The word sounds complicated, but it just means 'making something from light.'

Unlike plants, animals have to go find what they need. That's why animals move! • Food: animals eat. Plant-eaters (herbivores) eat leaves, seeds, and fruit. Meat-eaters (carnivores) hunt other animals. Animals that eat both are called omnivores — like bears, raccoons, and humans. • Water: animals drink from rivers, streams, and puddles. Some animals, like desert mice, get almost all their water from the seeds and berries they eat. • Air: most animals breathe air with lungs. Fish use gills to pull oxygen from water. Insects breathe through tiny tubes along their bodies. • Shelter: animals build, dig, or find safe places to rest. Robins build cup-shaped nests from grass and twigs. Beavers build lodges in rivers from sticks and mud. Prairie dogs dig underground tunnels called burrows. Each shelter keeps the animal safe from weather and predators.