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Invertebrate
| Invertebrates Temporal range: Cryogenian to Present,
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| 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). | |
Scientific classification
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| Domain: | Eukaryota |
| Clade: | Choanozoa |
| Kingdom: | Animalia |
| Groups included | |
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Invertebrates is an umbrella term describing 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, mollusks, annelids, echinoderms, flatworms, cnidarians, and sponges.
The majority of animal species are invertebrates; one estimate puts the figure at 97%.[1] Many invertebrate taxa have a greater number and diversity of species than the entire subphylum of Vertebrata.[2] Invertebrates vary widely in size, from 10 μm (0.0004 in)[3] myxozoans to the 9–10 m (30–33 ft) colossal squid.[4]
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 term "invertebrates" rather polyphyletic, so the term has little meaning in taxonomy.
- ^ May, Robert M. (16 September 1988). "How Many Species Are There on Earth?". Science. 241 (4872): 1441–9. Bibcode:1988Sci...241.1441M. doi:10.1126/science.241.4872.1441. JSTOR 1702670. PMID 17790039. S2CID 34992724. Archived from the original on 15 November 2016. Retrieved 17 June 2014.
- ^ Richards, O. W.; Davies, R.G. (1977). Imms' General Textbook of Entomology: Volume 1: Structure, Physiology and Development Volume 2: Classification and Biology. Berlin: Springer. ISBN 978-0-412-61390-6.
- ^ Canning, Elizabeth U.; Okamura, Beth (1 January 2003). "Biodiversity and Evolution of the Myxozoa". Advances in Parasitology. Vol. 56. Academic Press. pp. 43–131. doi:10.1016/S0065-308X(03)56002-X. ISBN 978-0-12-031756-1. PMID 14710996.
- ^ Roper, C.F.E. & P. Jereb (2010). Family Cranchiidae. In: P. Jereb & C.F.E. Roper (eds.) Cephalopods of the world. An annotated and illustrated catalogue of species known to date. Volume 2. Myopsid and Oegopsid Squids Archived 29 January 2019 at the Wayback Machine. FAO Species Catalogue for Fishery Purposes No. 4, Vol. 2. FAO, Rome. pp. 148–178.
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