Invertebrate

| image = Invertebrate montage (2022).jpg | image_upright = 1.2 | image_alt = Diversity of various invertebrates from different phyla (including a invertebrate of the phylum Chordata) | image_caption = Left to right: ''Chrysaora fuscescens'' (Cnidaria), ''Fromia indica'' (Echinodermata), Caribbean reef squid (Mollusca), ''Drosophila melanogaster'' (Arthropoda), ''Aplysina lacunosa'' (Porifera), ''Pseudobiceros hancockanus'' (Platyhelminthes), ''Hirudo medicinalis'' (Annelida), ''Polycarpa aurata'' (Tunicata), ''Milnesium tardigradum'' (Tardigrada). | auto = yes | parent = Animalia | includes = *All animal groups not in subphylum Vertebrata }} Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordate subphylum Vertebrata, i.e. vertebrates. Well-known phyla of invertebrates include arthropods, molluscs, annelids, echinoderms, flatworms, cnidarians, and sponges.

The majority of animal species are invertebrates; one estimate puts the figure at 97%. Many invertebrate taxa have a greater number and diversity of species than the entire subphylum of Vertebrata. Invertebrates vary widely in size, from 10 μm (0.0004 in) myxozoans to the 9–10 m (30–33 ft) colossal squid.

Some so-called invertebrates, such as the Tunicata and Cephalochordata, are actually sister chordate subphyla to Vertebrata, being more closely related to vertebrates than to other invertebrates. This makes the "invertebrates" paraphyletic, so the term has no significance in taxonomy. Provided by Wikipedia