How do organisms obtain energy?
An autotroph is an organism who makes its own food (example: flower). A heterotrophs is an organism who has to consume its own food from a source other than itself (example: human). A decomposer is an organism who breaks down its food (example: mushroom).
One chain from the desert food web is the rodents get eaten by the snake, which get eaten by the fox. One chain from the taiga food web is the grass gets eaten by the squirrel, which gets eaten by the bobcat, which gets eaten by the bear.
How does energy flow through an ecosystem?
Food chains and food webs deal with both matter and energy. When ecologists want to focus only on energy, they use another type of model--an ecological pyramid.
In each Pyramid from bottom to top it decreases by 10%.