Editing Tick (section)

===Anatomy and physiology===
[[File:Amblyomma americanum tick.jpg|thumb|left|A hard-bodied tick of the family Ixodidae, [[Amblyomma americanum|the lone star tick]]]]

Ticks, like [[mites]], belong to the subclass Acari that lack their primary somatic segmentation of the [[Abdomen#Arthropoda|abdomen]] (or [[opisthosoma]]), rather these parasitic [[arachnid]]s present a subsequent fusion of the abdomen with the [[cephalothorax]] (or [[prosoma]]).<ref name=Ruppert/> The [[Tagma (biology)|tagmata]] typical of other [[Chelicerata]] have developed into the [[gnathosoma]] (head), which is retractable and contains the mouthparts, and idiosoma (body), which contains the legs, digestive tract, and reproductive organs.<ref name="Wall-55" /> The gnathosoma is a feeding structure with mouthparts adapted for piercing skin and sucking blood; it is the front of the head and contains neither the brain nor the eyes.<ref name=Ruppert>{{cite book |title=Invertebrate Zoology | edition = 7th | vauthors = Ruppert EE, Fox RS, Barnes RD |year=2004 |publisher=Cengage Learning |isbn=978-81-315-0104-7 |pages=590–595 }}</ref> Features of the gnathosoma include two [[palp]]s, two [[chelicera]]e, and [[hypostome]]. The hypostome acts as stabilizer and helps to anchor the tick's mouthparts to the host.<ref>{{cite journal | vauthors = Richter D, Matuschka FR, Spielman A, Mahadevan L | title = How ticks get under your skin: insertion mechanics of the feeding apparatus of Ixodes ricinus ticks | journal = Proceedings. Biological Sciences | volume = 280 | issue = 1773 | pages = 20131758 | date = December 2013 | pmid = 24174106 | pmc = 3826218 | doi = 10.1098/rspb.2013.1758 | issn = 0962-8452 }}</ref> The chelicerae are specialized appendages used for cutting and piercing into the host's skin while palps are leglike appendages that are sensory in function.

The ventral side of the idiosoma bears [[sclerite]]s, and the gonopore is located between the fourth pair of legs. In the absence of segmentation, the positioning of the eyes, limbs, and [[gonopore]] on the idiosoma provide the only locational guidance.<ref name=Ruppert/>

Larval ticks hatch with six legs, acquiring the other two after a blood meal and [[molting]] into the nymph stage.<ref name=illinois>{{cite web |title=Common Ticks |url=http://www.idph.state.il.us/envhealth/pccommonticks.htm |website=Illinois Department of Public Health |access-date=11 April 2014}}</ref> In the nymphal and adult stages, ticks have eight legs, each of which has seven segments and is tipped with a pair of claws. The legs are sometimes ornamented and usually bear sensory or tactile hairs.<ref name=CVBDlegs>{{cite web |url=http://www.cvbd.org/en/tick-borne-diseases/about-ticks/general-morphology/locomotion/ |title=Soft ticks |work=CVBD: Companion Vector-Borne Diseases |access-date=6 December 2016}}</ref> In addition to being used for [[Animal locomotion|locomotion]], the [[Arthropod leg#Tarsus|tarsus]] of leg I contains a unique sensory structure, [[Haller's organ]], which can detect odors and chemicals emanating from the host, as well as sensing changes in temperature and air currents.<ref name="Sonenshine-2005-p14" /><ref name="nicholson-486" /><ref>For Haller's organ, see also: [[#Mehlhorn|Mehlhorn (2008)]]: [https://books.google.com/books?id=Jpg1ysgVn-AC&pg=PA582 p. 582].</ref> Ticks can also use Haller's organs to perceive [[infrared]] light emanating from a host.<ref>{{cite journal | vauthors = Mitchell RD, Zhu J, Carr AL, Dhammi A, Cave G, Sonenshine DE, Roe RM | title = Infrared light detection by the haller's organ of adult american dog ticks, Dermacentor variabilis (Ixodida: Ixodidae) | journal = Ticks and Tick-Borne Diseases | volume = 8 | issue = 5 | pages = 764–771 | date = August 2017 | pmid = 28647127 | pmc = 5588665 | doi = 10.1016/j.ttbdis.2017.06.001 }}</ref>  When stationary, their legs remain tightly folded against the body.<ref name="Sonenshine-2005-p14">[[#Sonenshine|Sonenshine (2005)]]: [https://books.google.com/books?id=dKlUARLKT9IC&pg=PA14 p. 14]{{Dead link|date=March 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="nicholson-486">[[#Nicholson|Nicholson et al. (2009)]]: [https://books.google.com/books?id=6R1v9o-uaI4C&pg=PA486 p. 486]</ref>

Ticks are extremely resilient animals. They can survive in a near vacuum for as long as half an hour.<ref>{{cite web|url=http://blogs.discovermagazine.com/notrocketscience/2012/03/15/tick-vacuum-electron-microscope/|title=Stuffed in a vacuum and bombarded by electrons, a tick waves hello|date=15 March 2012|vauthors=Yonge|publisher=Discover|access-date=1 May 2019|archive-date=1 May 2019|archive-url=https://web.archive.org/web/20190501045656/http://blogs.discovermagazine.com/notrocketscience/2012/03/15/tick-vacuum-electron-microscope/|url-status=dead}}</ref> Their slow metabolism during their [[diapause|dormant periods]] enables them to go prolonged durations between meals.<ref>{{cite web|url=https://www.uc.edu/news/articles/2018/11/n2048879.html|title=UC study: Hungry ticks work harder to find you|publisher=UC Cincinnati| vauthors = Miller M |date=20 November 2018}}</ref> Even after 18 weeks of starvation, they can endure repeated two-day bouts of dehydration followed by rehydration, but their survivability against dehydration drops rapidly after 36 weeks of starvation.<ref>{{cite journal | vauthors = Rosendale AJ, Dunlevy ME, Fieler AM, Farrow DW, Davies B, Benoit JB | title = Dehydration and starvation yield energetic consequences that affect survival of the American dog tick | journal = Journal of Insect Physiology | volume = 101 | pages = 39–46 | date = August 2017 | pmid = 28648807 | doi = 10.1016/j.jinsphys.2017.06.012 | doi-access = free | bibcode = 2017JInsP.101...39R }}</ref> To keep from dehydrating, ticks hide in humid spots on the forest floor<ref>{{cite web|url=https://www.outsideonline.com/1915071/rise-tick|title=The Rise of the Tick | vauthors = Zimmer C |publisher=Outside|date=30 April 2013}}</ref> or absorb water from subsaturated air by secreting [[Hygroscopy|hygroscopic]] fluid produced by the [[salivary gland]]s onto the external mouthparts and then reingesting the water-enriched fluid.<ref>{{cite journal | vauthors = Gray JS, Kahl O, Lane RS, Levin ML, Tsao JI | title = Diapause in ticks of the medically important Ixodes ricinus species complex | journal = Ticks and Tick-Borne Diseases | volume = 7 | issue = 5 | pages = 992–1003 | date = July 2016 | pmid = 27263092 | pmc = 5659180 | doi = 10.1016/j.ttbdis.2016.05.006 }}</ref>

Ticks can withstand temperatures just above {{convert|0|°F|°C|order=flip}} for more than two hours and can survive temperatures between {{convert|20 and 29|F|C|order=flip}} for at least two weeks. Ticks have even been found in Antarctica, where they feed on penguins.<ref>{{cite web|url=https://www.sciencedaily.com/releases/2017/09/170925133016.htm|title=Ticks are even tougher and nastier than you thought|date=25 September 2017|website=Science Daily}}</ref>

Most ticks are plain brown or reddish brown. However, the scuta of some species are decorated with white patterns.<ref>{{cite book|title=Laboratory Procedures for Veterinary Technicians| vauthors = Sirois M |publisher=Elsevier|year=2015|isbn=978-0-323-16930-1|location=St. Louis, MO}}</ref>

====Ixodidae====

In [[Nymph (biology)|nymphs]] and adults, the {{lang|la|capitulum}} is prominent and projects forwards from the body. The eyes are close to the sides of the scutum and the large [[Spiracle (arthropods)|spiracle]]s are located just behind the [[Arthropod leg|coxae]] of the fourth pair of legs.<ref name="Molyneux">[[#Molyneux|Molyneux (1993)]] [https://books.google.com/books?id=jj18axV3TTAC&pg=PA6 p. 6]</ref> The hard protective [[scutellum (insect anatomy)|scutellum]], a characteristic of this family, covers nearly the whole dorsal surface in males, but is restricted to a small, shield-like structure behind the capitulum in females and nymphs.<ref name="Walker">{{cite book | vauthors = Walker JB, Keirans JE, Horak IG |title=The Genus ''Rhipicephalus'' (Acari, Ixodidae): A Guide to the Brown Ticks of the World |url=https://books.google.com/books?id=M9fLCgAAQBAJ&pg=PA39 |year=2005 |publisher=Cambridge University Press |isbn=978-1-316-58374-6 |page=39}}</ref> When an ixodid attaches to a host the bite is typically painless and generally goes unnoticed. They remain in place until they engorge and are ready to [[Moulting|molt]]; this process may take days or weeks. Some species drop off the host to molt in a safe place, whereas others remain on the same host and only drop off once they are ready to lay their eggs.<ref name=Salman>{{cite book| vauthors = Salman MD, Tarrés-Call J, Estrada-Peña A |title=Ticks and Tick-borne Diseases: Geographical Distribution and Control Strategies in the Euro-Asia Region |url=https://books.google.com/books?id=mN4gCC81XHcC&pg=PA6 |year=2013 |publisher=CABI |isbn=978-1-84593-853-6 |pages=6–12}}</ref>[[File:Argas spec columbidae.jpg|thumb|A soft-bodied tick of the family Argasidae, beside eggs it has just laid]]

====Argasidae====

The body of a soft tick is pear-shaped or oval with a rounded anterior portion. The mouthparts cannot be seen from above, as they are on the ventral surface. A centrally positioned dorsal plate with ridges projecting slightly above the surrounding surface, but with no decoration is often present. Soft ticks possess a leathery [[cuticle]] as well. A pattern of small, circular depressions expose where muscles are attached to the interior of the [[integument]]. The eyes are on the sides of the body, the spiracles open between legs 3 and 4, and males and females only differ in the structure of the genital pore.<ref name="CVBDsoft">{{cite web |url=http://www.cvbd.org/en/tick-borne-diseases/about-ticks/general-morphology/soft-ticks/ |title=Soft ticks |work=CVBD: Companion Vector-Borne Diseases |access-date=6 December 2016|archive-url=https://web.archive.org/web/20190124004932/http://www.cvbd.org/en/tick-borne-diseases/about-ticks/general-morphology/soft-ticks/|archive-date=24 January 2019|url-status=live}}</ref>

====Nuttalliellidae====

Nuttalliellidae can be distinguished from both ixodid and argasid ticks by a combination of a projecting gnathosoma and a soft leathery skin. Other distinguishing characteristics include the position of the [https://web.archive.org/web/20181112221807/http://idtools.org/id/mites/invasive_mite/Invasive_Mite_Identification/key/Major_Mite_taxa/Media/Html/21_Peritremes.htm stigmata], the lack of setae, the strongly corrugated integument, and the form of the fenestrated plates.<ref>[[#Roshdy|Roshdy et al. (1983)]]</ref><ref>{{cite news |title=Long Lost Relative of Ticks Pops Up Again | vauthors = Brouwers L | url=http://blogs.scientificamerican.com/thoughtomics/a-long-lost-relative-of-ticks-pops-up-again/ |newspaper=Scientific American |date=30 August 2011 |access-date=4 December 2016}}</ref>