Editing Mite (section)

==Anatomy==

===External===
Mites are tiny members of the class [[Arachnid]]a; most are in the size range {{convert|250|to|750|µm|in|2|abbr=on}} but some are larger and some are no bigger than {{convert|100|µm|in|3|abbr=on}} as adults. The body plan has two [[tagma (biology)|regions]], a [[cephalothorax]] (with no separate head) or prosoma, and an [[opisthosoma]] or abdomen. Segmentation has almost entirely been lost and the prosoma and opisthosoma are fused, only the positioning of the limbs indicating the location of the segments.<ref name=Ruppert/>

[[File:Acarine anatomy and morphology.png|thumb|right|upright=1.6|1 Chelicerae, 2 Palps, 3 Salivary glands, 4 Gut, 5 Excretory (Malpighian) tubules, 6 Anus, 7 Ovary or testes, 8 Air-breathing tubes (tracheae), 9 Central ganglion, 10 Legs, 11 Hypostome.<ref>{{cite journal | vauthors = Balashov YS | year = 1972 | title = Bloodsucking Ticks - Vectors of Diseases of Man and Animals | journal = Miscellaneous Publications of the Entomological Society of America | volume = 8 | pages = 161–376 }}</ref>]]

At the front of the body is the [[gnathosoma]] or capitulum. This is not a head and does not contain the eyes or the brain, but is a retractable feeding apparatus consisting of the [[chelicerae]], the [[pedipalp]]s and the oral cavity. It is covered above by an extension of the body [[carapace]] and is connected to the body by a flexible section of [[cuticle]]. 
Two-segmented chelicerae is the ancestral condition in Acariformes, but in more derived groups they are single-segmented. And three-segmented chelicerae is the ancestral condition in Parasitiformes, but has been reduced to just two segments in more derived groups.<ref>[https://books.google.com/books?id=o2t2BgAAQBAJ&dq=Ancestrally+chelicera+two-segmented+Acariformes+Parasitiformes+three-segmented&pg=PA266 Parasite Diversity and Diversification]</ref> The pedipalps differ between taxa depending on diet; in some species the appendages resemble legs while in others they are modified into chelicerae-like structures. The oral cavity connects posteriorly to the mouth and [[pharynx]].<ref name=Ruppert/>

Most mites have four pairs of legs (two pairs in [[Eriophyoidea]]<ref>{{Citation | vauthors = Hoy MA |title=Four-Legged Mites (Eriophyoidea or Tetrapodili) |date=2004 |url=http://link.springer.com/10.1007/0-306-48380-7_1689 |encyclopedia=Encyclopedia of Entomology |pages=913–919 |place=Dordrecht |publisher=Kluwer Academic Publishers |language=en |doi=10.1007/0-306-48380-7_1689 |isbn=978-0-7923-8670-4 |access-date=2023-02-08|url-access=subscription }}</ref>), each with six segments, which may be modified for swimming or other purposes. The dorsal surface of the body is clad in hardened [[Tergum|tergites]] and the ventral surface by hardened [[sclerite]]s; sometimes these form transverse ridges. The [[gonopore]] (genital opening) is located on the ventral surface between the fourth pair of legs. Some species have one to five median or lateral eyes but many species are blind, and slit and pit sense organs are common. Both body and limbs bear [[seta]]e (bristles) which may be simple, flattened, club-shaped or sensory. Mites are usually some shade of brown, but some species are red, orange, black or green, or some combination of these colours.<ref name=Ruppert/>

Many mites have stigmata (openings used in respiration). In some mites, the stigmata are associated with [[peritreme]]s: paired, tubular, elaborated extensions of the tracheal system. The higher taxa of mites are defined by these structures:<ref>{{Cite web |title=Glossary |url=https://idtools.org/bee_mite/index.cfm?pageID=14 |access-date=2023-06-26 |website=Bee Mite ID}}</ref><ref name=":02">{{Cite web |title=All mites have a small head |url=https://keys.lucidcentral.org/keys/mites/qmites/html/21_Peritremes.htm |access-date=2023-06-26 |website=keys.lucidcentral.org}}</ref><ref name=":12">{{Cite book | vauthors = Krantz GW |title=A Manual of Acarology |date=2009 |publisher=Texas Tech University Press |isbn=978-0-89672-620-8 |edition=3rd |location=Lubbock, Tex |language=English |chapter=Form and Function | veditors = Krantz GW, Walter DE }}</ref>

* Oribatida, formerly known as Cryptostigmata ([[wiktionary:crypto-|crypto-]] = hidden), and Endeostigmata (endeo- = internal) lack primary stigmata and peritremes but may have secondary respiratory systems.<ref>{{Cite web |title=Acariformes |url=https://keys.lucidcentral.org/keys/mites/qmites/html/Sarcoptiformes.htm |access-date=2023-06-27 |website=keys.lucidcentral.org}}</ref> For example, oribatids in the suborder [[Brachypylina]] have stigmata on the ventral plate of the body that are difficult to see (thus the former name Cryptostigmata).<ref>{{Cite book | vauthors = Norton RA, Behan-Pelletier VM |title=A manual of acarology |date=2009 |publisher=Texas Tech Univ. Press |isbn=978-0-89672-620-8 | veditors = Krantz GW, Walter DE |edition=3rd |location=Lubbock, Tex |chapter=Suborder Oribatida }}</ref>
* Astigmata ([[wiktionary:a-|a-]] = without) lack stigmata and respire through their cuticle.<ref>{{Cite web |date=2022-06-03 |title=Astigmata Sarcoptiformes - Urban Insects |url=https://www.insectomania.org/urban-insects/astigmata-sarcoptiformes.html |access-date=2023-06-26 |website=Insectomania |language=en}}</ref>
* Prostigmata ([[wiktionary:pro-|pro-]] = before/in front) have stigmata at the front of the body, usually on the lateral margins or between the chelicerae. These are associated with peritremes that may be on the prodorsum near the cheliceral bases, or be horn-like and emergent, or form a line or network on the dorsum of the gnathosomal capsule.<ref name=":02" />
* Opilioacaridae have four pairs of dorsolateral stigmata that are added sequentially during development.<ref name=":02" />
* The other three orders of Parasitiformes, Holothyrida, Ixodida, and Mesostigmata ([[wiktionary:meso-|meso-]] = middle), have just one pair of stigmata in the region of the fourth pair of legs. They also have peritremes: in Ixodida these consist of paired encircling plates around the stigmata, while the peritremes in Mesostigmata and Holothyrida are grooves extending from the stigmata anteriorly (sometimes also posteriorly).<ref name=":12" />

===Internal===
Mite digestive systems have [[Salivary gland|salivary glands]] that open into the preoral space rather than the foregut. Most species carry two to six pairs of salivary glands that empty at various points into the subcheliceral space.<ref>{{cite journal |vauthors=Shatrov AB |date=January 2005 |title=Ultrastructural investigations of the salivary glands in adults of the microtrombidiid mite Platytrombidium fasciatum (CL Koch, 1836)(Acariformes: Microtrombidiidae). |journal=Arthropod Structure & Development |volume=34 |issue=1 |pages=49–61 |doi=10.1016/j.asd.2004.09.001|bibcode=2005ArtSD..34...49S }}</ref> A few mite species lack an anus: they do not defecate during their short lives.<ref>{{cite magazine |date=27 August 2014 |title=You Almost Certainly Have Mites On Your Face |url=http://phenomena.nationalgeographic.com/2014/08/27/you-almost-certainly-have-mites-on-your-face/ |archive-url=https://web.archive.org/web/20140911205827/http://phenomena.nationalgeographic.com/2014/08/27/you-almost-certainly-have-mites-on-your-face/ |url-status=dead |archive-date=September 11, 2014 |magazine=National Geographic |access-date=23 November 2017 |vauthors=Yong E}}</ref> The circulatory system consists of a network of sinuses and most mites lack a heart, with movement of fluid being driven by the contraction of body muscles. Ticks, and some of the larger species of mites, have a dorsal, longitudinal heart.<ref>[https://books.google.com/books?id=61vuCAAAQBAJ&dq=Ticks+certain+mites+dorsal+longitudinal+heart&pg=PA50 Medical Entomology: A Textbook on Public Health and Veterinary Problems Caused by Arthropods]</ref> Gas exchange is carried out across the body surface, but many species additionally have between one and four pairs of [[Trachea|tracheae]]. The excretory system includes a [[nephridium]] and one or two pairs of [[Malpighian tubule|Malpighian tubules]].<ref name="Ruppert2">{{cite book |title=Invertebrate Zoology |vauthors=Ruppert EE, Fox RS, Barnes RD |publisher=Cengage Learning |year=2004 |isbn=978-81-315-0104-7 |edition=7th |pages=590–595}}</ref> Several families of mites, such as Tetranychidae, Eriophyidae, Camerobiidae, Cunaxidae, Trombidiidae, Trombiculidae, Erythraeidae and Bdellidae have [[silk]] glands used to produce silk for various purposes. Additionally, water mites (Hydrachnidia) produce long thin threads that may be silk.<ref>[https://kmkjournals.com/upload/PDF/Acarina/22/Acar22_2_133_148_Shatrov_et_al.pdf Observation on Silk Production and Morphology of Silk in Water Mites (Acariformes: Hydrachnidia)]</ref>