Food chains and poison

In a nutshell

Organisms depend on each other for food. Food chains are a way of showing what is eaten by what. Sometimes poison can enter food chains and cause harm to organisms. 

Food chains

Definition

A food chain is a diagram that shows the energy transfers between different organisms in an ecosystem.

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Example

The arrows show the direction in which energy gets passed on. Plankton is food for small fish and provides the small fish with energy. Small fish provide the squid with energy when the squid eats them.

Note: The arrow is always pointing at the organism that is eating the previous organism.

Poison in food chains

Sometimes poison builds up in food chains and causes harm to organisms. Animals at the top of food chains are normally the worst affected because the poison builds up as it is passed along the food chain. 

Example