Branchiopoda is a class of small aquatic crustaceans that includes familiar species like brine shrimp and water fleas. They are primarily found in freshwater environments, although some species inhabit saltwater. Branchiopods are characterized by their flattened bodies and numerous appendages, which they use for swimming and feeding. These creatures play a vital role in aquatic ecosystems as they serve as a food source for fish and other animals. Branchiopods are also important for nutrient cycling in their habitats, as they help break down organic matter and contribute to the overall health of the ecosystem.