Copepods are the 'water fleas of the sea'. Despite the fact that they are extremely small, they are found in the sea in enormous amounts. They belong to the group of zooplankton. They gather their food from the water with the help of a fine-meshed net of brush hairs located on sections of their mouth. They eat animals and algae smaller than themselves. Lots of marine animals, for example, barnacles, shellfish, sea squirts, fish such as herring and mackerel and even various species of whales, live off of these mini-crustaceans. This makes copepods the most important link between the microscopic plankton and the other animal life in the sea.