Invertebrates are a comprehensive classification encompassing animals that lack a vertebral column, which originated from the notochord. This term represents a paraphyletic category that comprises all animals apart from the chordate subphylum Vertebrata, which encompasses vertebrates. Some notable phyla within the category of invertebrates include arthropods, molluscs, annelids, echinoderms, flatworms, cnidarians, and sponges.
