The term for a living organism that has no backbone is invertebrate. Invertebrates comprise a vast majority of animal species on Earth, making up approximately 95% of all animals. This group includes diverse organisms such as insects, arachnids, mollusks, and crustaceans. Invertebrates exhibit various forms and adaptations, allowing them to thrive in different habitats, from oceans to forests. Despite lacking a backbone, many invertebrates possess other structural features, such as exoskeletons or hydrostatic skeletons, which provide support and protection. Their importance to ecosystems, such as pollination and decomposition, is fundamental to environmental health.