Darkfield illuminated polarised light micrograph of a Cyclops sp. copepod carrying eggs (small, round). Copepods are microscopic aquatic crustaceans found in waters around the world. They may either be free living or parasitic on other organisms and are the main constituent of zooplankton. They feed on other microscopic animals and plants. Cyclops copepods are one of the most common freshwater copepods. Magnification: x70 when printed at 10 centimetres wide at its longest edge.