Copepods are tiny crustaceans found in oceans, freshwater, and even in some moist environments. They play a crucial role in aquatic ecosystems as a primary food source for many fish and other marine animals. Copepods vary in size, typically ranging from 0.2 to 20 millimeters, and can be identified by their elongated bodies and large antennae, which they use for swimming. These organisms are incredibly diverse, with thousands of species identified worldwide. Copepods contribute significantly to the marine food web and are essential for nutrient cycling in aquatic environments. Their ability to reproduce quickly allows them to adapt to changing conditions, making them resilient inhabitants of various habitats.