This document discusses organisms, species, and some examples of microorganisms that can be found in an ecosystem. It provides the following information: - An organism is any living thing, while a species is a group of similar organisms that can reproduce. - There are macro-organisms and micro-organisms, with the latter being too small to see with the naked eye. - Examples of micro-organisms that will be looked for include Cyclops, Daphnia, seed shrimp, water mites, roundworms, Paramecium, and caddisfly larvae.