An animal with no backbone is termed an invertebrate. Invertebrates comprise the majority of animal species on Earth and include a diverse array of organisms such as insects, arachnids, mollusks, and crustaceans. They play crucial roles in ecosystems, contributing to pollination, decomposition, and as a food source for vertebrates. Invertebrates exhibit a variety of body structures and adaptations, allowing them to thrive in different environments. Despite lacking a backbone, many invertebrates possess hard exoskeletons or shells that provide support and protection, showcasing their evolutionary success.