Living things in their environment

Living organisms are found almost everywhere on our planet - on land, in the air, in water, underground. Some have even colonised the structures we have built. We share our homes, and even our bodies, with a variety of other organisms.

Wasps and the house mouse are examples of organisms which have colonised our homes.

The place where an organism occurs is known as its 'habitat'. The habitat is dependent on environmental factors such as temperature, rainfall, location, medium (soil, water, air etc.), vegetation and so on.

• Adaptation
  Different habitats support different organisms
  Adaptation to daily and seasonal changes in habitat
• Feeding relationships
  Food chains
  Food webs Accumulation of toxic materials in a food chain
• Competition
  Factors affecting populations size
  Successful organisms

Life on Earth has adapted to survive in many different habitats - from the heat of the desert to the depths of the oceans.

Different habitats support different organisms

The conditions present in an organism's habitat make up its environment. These include things like temperature, humidity, light levels and the presence of other organisms. For example, plants grow in most places on Earth, but the weather conditions in Europe in winter mean that many plants have a 'rest' season when they shed their leaves. In the tropics leaves are shed throughout the year since the temperature is more or less constant (for more on this see 'Adaptation to daily and seasonal changes in habitat').

Although these are both forests, the different conditions in the Amazon (left) and Europe (right) make these very different habitats.