Invertebrate immunity refers to the defense mechanisms that protect animals without a backbone, such as insects, mollusks, and crustaceans. Unlike vertebrates, invertebrates lack a complex adaptive immune system. Instead, they rely on innate immunity, which includes physical barriers like exoskeletons and cellular responses involving hemocytes that can engulf pathogens. Invertebrates also produce antimicrobial peptides that target and destroy harmful microorganisms. Their immune responses are often rapid and non-specific, allowing them to respond quickly to infections. This system is crucial for their survival in diverse environments, where they encounter various pathogens and threats.