Editing Mygalomorphae (section)

==Description==
This group of spiders comprises mostly heavy-bodied, stout-legged spiders including [[tarantula]]s, [[Australian funnel-web spider]]s, [[mouse spider]]s, and various families of spiders commonly called [[trapdoor spider]]s.

Like the "[[Primitive (biology)|primitive]]" suborder of spiders [[Mesothelae]], they have two pairs of [[book lungs]], and downward-pointing [[chelicerae]]. Because of this, the two groups were once believed to be closely related. Later it was realised  that the common ancestors of all spiders had these features (a state known as [[symplesiomorphy]]). Following the branching into the suborders of Mesothelae and  [[Opisthothelae]], the mygalomorphs retained them, while their fellow Opisthothelae members, the [[araneomorph]]s, evolved new "modern" features, including a [[cribellum]] and cross-acting fangs.<ref name=CoddLevi91/> Mesotheles retain the external abdominal segmentation of ancestral arachnids and have at least vestiges of four pairs of spinnerets, whereas mygalomorphs lack abdominal segmentation (like other opistotheles) and have a reduced number of spinnerets, often only two pairs.<ref name=WheeCoddCrowDimi16/>

Like spiders in general, most species of Mygalomorphae have eight eyes, one pair of principal and three pairs of secondary eyes.

[[Image:Black Wishbone.jpg|thumb|Chelicerae of a [[Aname atra|black wishbone spider]] ([[Nemesiidae]])]]

Their chelicerae and fangs are large and powerful and have ample [[venom]] glands that lie entirely within their [[chelicerae]]. These weapons, combined with their size and strength, make Mygalomorph spiders powerful predators. Many of these spiders are well adapted to killing other large arthropods and will also sometimes kill small [[mammal]]s, [[bird]]s, and [[reptile]]s. Despite their fearsome appearance and reputation, most mygalomorph spiders are not harmful to humans, with the exception of the [[Australian funnel-web spider]]s, especially those of the genus ''[[Atrax]]''.{{citation needed|date=February 2017}}

While the world's biggest spiders are mygalomorphs – ''[[Theraphosa blondi]]'' has a body length of {{convert|10|cm|abbr=on}} and a leg span of {{convert|28|cm|abbr=on}} – some species are less than {{convert|1|mm|spell=in|sp=us}} long. Mygalomorphs are capable of spinning at least slightly adhesive silk, and some build elaborate capture webs that approach a metre in diameter.<ref name=CoddLevi91/>

Unlike [[Araneomorphae]], which die after about a year, Mygalomorphae can live for up to 25&nbsp;years, and some do not reach maturity until they are about six years old.<ref name=CSIRO_spiders/> Some flies in the family [[Acroceridae]] that are [[endoparasite]]s of mygalomorphs may remain dormant in their book lungs for as long as 10&nbsp;years before beginning their development and consuming the spider.<ref>{{cite book |last1=Schlinger |first1=Evert I. |editor1-last=Nentwig |editor1-first=W |title=Ecophysiology of Spiders |date=1987 |publisher=Springer |isbn=978-3-642-71552-5 |pages=319–327 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-642-71552-5_24 |access-date=14 November 2024 |language=en |chapter=The Biology of Acroceridae (Diptera): True Endoparasitoids of Spiders|doi=10.1007/978-3-642-71552-5_24 }}</ref>

One female trapdoor spider, first recorded in a survey in 1974 in Western Australia, is known to have lived for 43&nbsp;years.<ref>{{cite news |title=World's oldest spider dies aged&nbsp;43 in Western Australia |date=28 April 2018 |website=ABC News |publisher=Australian Broadcasting Corporation |url=http://www.abc.net.au/news/2018-04-28/worlds-oldest-spider-dies-aged-43-in-western-australia/9707422 |access-date=2018-04-29 |archive-url=https://web.archive.org/web/20180429062001/http://www.abc.net.au/news/2018-04-28/worlds-oldest-spider-dies-aged-43-in-western-australia/9707422 |archive-date=2018-04-29}}</ref>