The term "Water Flea" commonly refers to small, aquatic crustaceans belonging to the order Cladocera. These tiny creatures, often less than 1 cm in length, are found in freshwater environments like ponds and lakes. They play a crucial role in the ecosystem by serving as a food source for fish and other aquatic animals. Water fleas have a distinctive body shape, typically with a transparent, oval body and large antennae that help them swim. They feed on algae and other microscopic organisms, contributing to the balance of aquatic ecosystems. Some species, like Daphnia, are widely studied in scientific research due to their sensitivity to environmental changes.