8D Pyramids of numbers In this pyramid of numbers there is lots of grass. The wide bar shows this. Lots of animals live on the grass. But there are fewer hares than grass plants so the bar is narrower. It takes quite a lot of hares to feed one eagle so the third layer up is even narrower. What trophic levels are the grass, the hares, and eagles? eagle grass hare Pyramids of Number

8D Strange pyramids! Here’s a strange pyramid! How does it work? This layer includes all the leaf-eating insects like caterpillars. A single oak tree can have millions of these! This layer includes the birds and animals that eat the insects. Now we’re back to sensible pyramids! This layer is a large old oak tree. It’s huge but there’s only one so the bar is very narrow. caterpillar oak tree blackbird Pyramids of Number

8D Pyramids of biomass Another way to look at pyramids is to measure the dry mass (biomass) of living materials at each level. These are called pyramids of biomass and they are always pyramid shaped. Why? grass hare eagle oak tree caterpillar blackbird Pyramids of Biomass

8D Explaining pyramids The primary producers can capture lots of energy from the Sun. They grow and reproduce very well to make a large population. When a rabbit eats grass some of the energy is lost. This passes out in faeces or is used just keeping the rabbit alive. The same is true for the foxes that eat the rabbits, so the next layer up has even fewer animals. Pyramids of numbers make sense because of the energy lost between levels.