Living together
In an ecosystem, no organism lives alone. Interdependence means living things depend on one another and on their environment for food, shelter, oxygen and other needs. These relationships keep the ecosystem stable.
Types of interaction
Organisms interact in several ways:
- Prey and predator — one animal hunts and eats another, such as an owl catching a mouse.
- Competition — organisms compete for the same limited resource, such as two plants competing for sunlight.
- Symbiosis — a close relationship between two different species living together.
Key idea
There are three main types of symbiosis: commensalism (one benefits, the other is unaffected), mutualism (both benefit) and parasitism (one benefits while the other is harmed).
Living and non-living factors
Organisms also interact with non-living (abiotic) factors such as sunlight, water, temperature and soil. For example, plants need sunlight and water to grow, and these in turn shape which animals can live in the area.
Example
A bird building its nest in a tree gains shelter while the tree is unharmed — this is commensalism, one type of symbiosis.
Remember
- Interdependence means organisms depend on one another.
- Mutualism: both benefit; parasitism: one is harmed.
- Abiotic factors include light, water, temperature and soil.