A butterfly drinks nectar from a flower. A robin builds a nest in a tree

A butterfly drinks nectar from a flower. A robin builds a nest in a
tree. A hawk swoops down and catches a rabbit. These are all
examples of interactions between living things and parts of their
Living things interact with
their ecosystem in different
ways. Sometimes these
interactions help one of the
organisms but harm
another. For example, some
organisms are predators
that hunt prey. During a
predator-prey interaction,
the predator benefits. It gets
food by catching and eating
the prey. However, the prey
organism dies. Examples of
predator-prey interactions
include frogs catching and
eating mosquitoes and
cheetahs catching and eating
other animals.
Sometimes the interactions between organisms help both living
things. For example, when a bee drinks nectar from a flower, it gets
pollen on its body. When it flies to another flower, the bee rubs the
pollen onto it. The bee benefits from the interaction because it gets
nectar to eat. The second flower benefits because the bee pollinates
it. When a flower is pollinated, it is able to make seeds.
Egyptian plover birds and crocodiles also interact in a way that
benefits both animals. Crocodiles often get leeches on their skin.
The leeches are harmful to the crocodile. Egyptian plover birds pick
the leeches off the crocodiles and eat them. The birds benefit from
the interaction because they get food to eat. The crocodiles benefit
because they get rid of the harmful leeches.
Discovery Education Science
© 2007 Discovery Communications, LLC
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Interactions in Ecosystems
Living things also depend on nonliving things in their
ecosystem to survive. Water is a very important
nonliving thing. Frogs need to lay their eggs in water.
Fish depend on water to breathe. Plants take in water
through their roots. They use the water to help them
grow and make food.
Sunlight is another nonliving thing in an ecosystem.
Plants need sunlight to make food by a process called
photosynthesis. Some land organisms, such as lizards
and snakes, depend on sunlight to warm their bodies.
Wind is another nonliving part of an ecosystem.
Some plants, such as dandelions and maple trees,
depend on the wind to carry their seeds to new places.
Living things are constantly interacting with their
environment. They interact with both living and nonliving things.
And they depend on many of these interactions to be successful.
Discovery Education Science
© 2007 Discovery Communications, LLC
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