what is an invertebrate

An invertebrate is an animal that lacks a vertebral column or backbone. Invertebrates are the most diverse and numerous group of animals on Earth, with more than 90% of all living animal species being invertebrates. They are distributed into more than 30 phyla, and each phylum describes a valid taxon. Invertebrates can be found in a wide range of environments, including on land and in water. They are especially important as agricultural pests, parasites, or agents for the transmission of parasitic infections to humans and other vertebrates. Invertebrates serve as food for humans and are key elements in food chains that support birds, fish, and many other vertebrate species. Some common examples of invertebrates include insects, arachnids, crustaceans, snails, clams, and squid.