Aquatic invertebrates are animals without a backbone that live in water environments, such as oceans, rivers, and lakes. They include a diverse range of species, such as jellyfish, crabs, snails, and octopuses. These creatures play essential roles in aquatic ecosystems, serving as both predators and prey. Many aquatic invertebrates have unique adaptations that help them survive in their habitats. For example, mollusks like clams have hard shells for protection, while sea stars can regenerate lost arms. Their presence is crucial for maintaining the balance of aquatic food webs and contributing to nutrient cycling in their environments.