All ecosystems must have three basic kinds of nutritional interactions in order to be stable and self-sustaining.

- involve producers, consumers, and decomposers.

Producer/Autotroph- an organism is one that is capable of trapping the Sun's energy to make glucose/sugar in the process of photosynthesis.

-Ex: Plants and algae.

Consumer/Heterotroph- An organism which depends upon and eats other organisms for their food.

Categories of consumers:

" herbivore" eats primarily plant material

"carnivore" eats primarily other animals.

"omnivore" eats both plant and animal material.

Ex:Humans

Decomposer- is a special category of consumer organism.

-break down dead organic matter and change it to simpler nutrients which can be recycled in the ecosystem.