Pyramids of numbers
A A diagram that shows the relative numbers of organisms at each stage in a food chain. shows the population at each stage in a A sequence (usually shown as a diagram) of feeding relationships between organisms, showing which organisms eat what and the movement of energy through trophic levels.. It is drawn as a bar chart with the bars stacked on top of each other. The wider the bar, the more organisms it represents. The An organism that makes its own food by converting light energy into chemical energy (photosynthesis). always goes at the bottom of the pyramid.
Question
What can you say about the number of organisms as you move along the food chain from producer up the trophic levels?
The number of organisms generally decreases but there are exceptions.
Other pyramid shapes
Sometimes a pyramid of numbers does not look like a pyramid at all. These are known as inverted pyramids. This could happen if the producer is a large plant, such as a tree, or if one of the animals is very small. Here are two examples.