Water fleas are small, aquatic crustaceans belonging to the class Branchiopoda. They are commonly found in freshwater environments, such as ponds and lakes. The most well-known species is Daphnia, which is often used in scientific research and as a food source for fish. Water fleas are characterized by their transparent bodies and large, prominent antennae, which they use for swimming. These tiny creatures play a vital role in the ecosystem by serving as a food source for various aquatic animals, including fish and amphibians. Water fleas feed on algae and other microorganisms, helping to maintain water quality. Their presence indicates a healthy aquatic environment, making them important indicators of ecosystem health.