Each animal in a food chain eats another and gains energy, this keeps the ecosystem alive.
Putting this food chain into a pyramid will look like this:
1 Barn owl
25 voles
200 grass seeds
10 Bluetits
200 Caterplillars
1 Tree
If this happens then in order to make it look like a pyramid you can change it into a 'pyramid of biomass' this shows the mass of living material rather than the numbers.
~ Animals that are hunted are care known as the prey.
~ Animals that hunt and eat other animals are called predators.