Entognatha

{{Short description|Class of wingless and ametabolous arthropods}}

{{Paraphyletic group|auto=yes

| image = Protura specimen (Acerentomon species) micrograph.jpg

| image_caption = Proturan specimen (Acerentomon sp.)

| display_parents = 2

| taxon = Entognatha

| authority =

| includes =

• Diplura (two-pronged bristletails)
• Collembola (springtails)
• Protura (coneheads)

| excludes = Insecta (insects)

}}

File:Two-pronged Bristletail (Diplura) (10353381334).jpg, a Two-pronged Bristletail — not closely related to three-pronged bristletails in the Archaeognatha}}]]

File:Katianna oceanica (13913339330).jpg}}]]

The Entognatha, from Ancient Greek ἐντός (entós), meaning "inside", and γνάθος (gnáthos), meaning "jaw", are a class of wingless and ametabolous arthropods, which, together with the insects, makes up the subphylum Hexapoda.{{cite book |author=David A. Grimaldi & Michael S. Engel |year=2005 |title=Evolution of the Insects |publisher=Cambridge University Press |isbn=978-0-521-82149-0 |chapter=Arthropods and the origin of insects |pages=93–118 |chapter-url=https://books.google.com/books?id=Ql6Jl6wKb88C&pg=PA111}}{{cite book |author=P. J. Gullan, Peter Cranston |year=2010 |title=The Insects: An Outline of Entomology |edition=4th |publisher=John Wiley and Sons |isbn=978-1-4443-3036-6 |chapter=Insect systematics: phylogeny and classification |pages=189–222 |chapter-url=https://books.google.com/books?id=S7yGZasJ7nEC&pg=PA201}} Their mouthparts are entognathous, meaning that they are retracted within the head, unlike the insects. Entognatha are apterous, meaning that they lack wings. The class contains three orders: Collembola (springtails, 9000 species),{{cite journal | pmc=7365838 | year=2020 | last1=Ospina-Sánchez | first1=C. M. | last2=Soto-Adames | first2=F. N. | last3=González | first3=G. | title=Checklist and distribution of Collembola from Greater Puerto Rico | journal=Biodiversity Data Journal | volume=8 | pages=e52054 | doi=10.3897/BDJ.8.e52054 | pmid=32733139 | doi-access=free }} Diplura ("two-tail", 1000 species){{Cite journal |doi=10.1111/icad.12480 |doi-access=free|title=Diversity, ecology, distribution and biogeography of Diplura |year=2021 |last1=Sendra |first1=Alberto |last2=Jiménez-Valverde |first2=Alberto |last3=Selfa |first3=Jesús |last4=Reboleira |first4=Ana Sofia P. S. |journal=Insect Conservation and Diversity |volume=14 |issue=4 |pages=415–425 |hdl=10550/82616 |hdl-access=free }} and Protura ("first-tail", 800 species).{{cite journal | pmc=6045683 | year=2018 | last1=Galli | first1=L. | last2=Shrubovych | first2=J. | last3=Bu | first3=Y. | last4=Zinni | first4=M. | title=Genera of the Protura of the World: Diagnosis, Distribution, and Key | journal=ZooKeys | issue=772 | pages=1–45 | doi=10.3897/zookeys.772.24410 | pmid=30018507 | doi-access=free | bibcode=2018ZooK..772....1G }} These three groups were historically united with the now-obsolete order Thysanura to form the class Apterygota, but it has since been recognized that the hexapodous condition of these animals has evolved independently from that of insects, and independently within each order.{{cite book |author=Alessandro Minelli |year=2009 |title=Perspectives in Animal Phylogeny and Evolution |publisher=Oxford University Press |isbn=978-0-19-856620-5 |chapter=A gallery of the major bilaterian clades |pages=71–109 |chapter-url=https://books.google.com/books?id=ood5LEkVTxcC&pg=PA101}} The orders might not be closely related, and Entognatha is now considered to be a paraphyletic group.