Surviving in an Ecosystem
Essential Question: How are the environment and an organism’s patterns of behavior related?
Ecosystems
A forest is an ecosystem. So is a pond or a meadow. An ecosystem is made up of all the living and nonliving things in a certain area. Plants and animals are living parts of an ecosystem. The nonliving parts include water, sunlight, soil, rocks, and air.
The diagram shows some of the living parts of a forest ecosystem. This area is home to many kinds of plants and animals. They include trees, foxes, hawks, insects, grasses, and mice. The animals act in certain ways to find food, water, air, shelter, and space.
Capstone eBook: A Journey Into Adaptation
Essential Question: How are the environment and an organism’s patterns of behavior related?
Ecosystems
A forest is an ecosystem. So is a pond or a meadow. An ecosystem is made up of all the living and nonliving things in a certain area. Plants and animals are living parts of an ecosystem. The nonliving parts include water, sunlight, soil, rocks, and air.
The diagram shows some of the living parts of a forest ecosystem. This area is home to many kinds of plants and animals. They include trees, foxes, hawks, insects, grasses, and mice. The animals act in certain ways to find food, water, air, shelter, and space.
Capstone eBook: A Journey Into Adaptation
Predators and Prey
You learned that plants can make their own food, but animals cannot. One of an animal’s most important behaviors is the way it gets food. It must find food in the ecosystem where it lives. Some animals eat only plants. Some animals eat other animals. An animal that hunts other animals for food is called a predator. The animal that is hunted is called prey. Hawks are predators. They hunt and eat small animals such as mice. The mice are the hawks’ prey. In a healthy ecosystem, predators and prey stay pretty much in balance. Hawks in a forest find enough mice and other small animals to stay alive. And there are enough mice to they are not all eaten by hawks. This kind of balance means that both hawks and mice will continue to live in the forest. But suppose a disease makes many mice get sick and die. Then the hawks may not have enough food. They may have to change their behavior to live. They many eat more of other kinds of prey, such as rabbits. If they cannot find other prey, some hawks will die, too. Others may leave the forest in search of food. |
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Competing for Resources
Living things in an ecosystem compete for food, water, sunlight, air, shelter, and space. To compete meant to try to get something that others also need or want. Hawks, owls, and snakes all hunt mice. They compete for the same food. If many mice get sick and die, only some animals will get the mice they need for food. Suppose the owls in a forest catch more mice than the hawks or snakes do. More owls will survive than hawks or snakes. Plants compete for what they need. A large tree’s leaves keep sunlight from reaching the ground. The tree also takes up large amounts of water and materials from the soil. The tree uses resources that other plants need. The tree may keep other plants from growing near it. When tall trees are cut down, smaller plants get more sunlight. Then more small plants are likely to grow. A long period without rain or with high temperatures can cause water to become scarce. A fire can wipe out trees and other plants that animals need for food and shelter. Some plants and animals will not survive. Some animals will move away. Different kinds of organisms may start to live in the ecosystem. |
Surviving Changing Seasons
Many places have cold winters. To survive, plants and animals change their behaviors. Many plants drop their leaves before winter. Not having leaves helps plants save water and protects them from cold temperatures. The plants stop making food, and stay alive by using food stored in their roots and stems. In winter, plants do not make flowers, fruits, or seeds. Seeds that are already in the soil do not spout until spring. Animals have a harder time finding food in winter. To survive, many animals hibernate. They spend the winter in a completely inactive condition, live a very deep sleep. They use so little energy that they do not need to eat. Chipmunks, groundhogs, and frogs are some animals that hibernate. Some animals move from place to place in a pattern with the seasons. These animals migrate. Migrating geese fly in the shape of a V. |
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