Our surroundings are full of living things and non-living things. Animals and plants come in the category of living things.
We know living things have the following characteristics:
1. They need air, water, sunlight, right climate, food and shelter to live.
2. They grow.
3. They are respond to stimuli.
4. They reproduce their own kind.
5. All living things have to die.
Non-living things do not have such characteristics.
There is enough air, water, sunlight and food on the earth so life exists on it. There is no life on the moon and other planets, because they lack these things.
There are two kinds of living things: (i) animals, including human beings; and (ii) plants.
Animals and plants depend upon each other. Animals depend wholly upon plants for food. Flesh and meat eating animals also depend upon plants, because flesh is got from animals, most of which eat plants. Animals also get fresh air due to plants because the plants let out oxygen during the day.
On the other hand, animals provide manure and carbon-dioxide to plants.
Plants and animals live in various places. They live in places where it is cold, as well as in places where it is hot and dry. They also live in rivers and lakes, and in the salty water of the oceans. Plants and animals living inside water should be able to breathe air dissolved in water. Those living in deserts should be able to survive with very little water.
Plants and animals living in a certain place survive by adapting themselves to the conditions of that place. For example, fishes have gills to breathe under water. They cannot survive outside water because they cannot breathe outside water. Cactus and camels can survive in deserts because they can store water in their bodies.
Because of the adaptations of their surroundings and natural phenomenon animals and plants living in different surroundings affect the shape size, color, style of life etc. That is why there are so many types of plants and animals that are differ from region to region.
For example, the leaves of a water lily plant that lives in water are thin and big, and float in water. They look very different from the leaves of a cactus plant, which are like sharp needles. Similarly a fish living in water has a different body structure as compared to animals living on land.
Thus in a certain type of climatic conditions and surroundings, specific types of animals and plants are found. A region having specific climatic conditions and accordingly specific types of animals and plants is called Habitat.