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Brief Summary

    Pholcidae: Brief Summary
    provided by wikipedia
    For other arthropods called "daddy longlegs", see Daddy longlegs.

    Pholcidae, commonly known as cellar spiders, are a spider family in the suborder Araneomorphae. The family contains about 1500 species divided into about 80 genera.

    Some species, especially Pholcus phalangioides, are commonly called daddy long-legs spider, granddaddy long-legs spider, carpenter spider, daddy long-legger, or vibrating spider. Confusion often arises because the name "daddy long-legs" is also applied to two distantly related arthropod groups: harvestmen (which are arachnids but not spiders) and crane flies (which are insects).

    Brief Summary
    provided by EOL authors

    The spider family Pholcidae (cellar spiders, daddylonglegs spiders) includes 1340 described species; the family is largely tropical, but several dozen species occur in North America north of Mexico, with the highest diversity in the southeastern United States (Huber 2005; Platnick 2013). In North America north of Mexico, six of the 12 genera found in this region are represented by introduced species only. Many pholcid species have adapted well to human habitats and are commonly found in corners and dark spaces in and around buildings, especially in basements. Pholcus phalangioides, for example, is common in buildings worldwide (Bradley 2013).

    The cephalothorax of a pholcid is typically about as long as it is wide. The legs are extremely long and thin (this feature accounts for one of the common names for spiders in this family, "daddylonglegs spiders", although unlike daddylonglegs, which are not actually spiders, they spin webs). The legs have flexible tarsi that are usually held in a curved position. Most pholcids have eight eyes, although some have only six. When long-legged pholcids are disturbed in their web, they move rapidly, flexing their legs so that the body gyrates in a circular motion. This may make them difficult to see and perhaps difficult for their main predators, wasps, to capture (Bradley 2013). Short-legged pholcids can run rapidly (Huber 2005).

    Pholcid females frequently carry their egg case in their chelicerae. The eggs are held together by a thin silken net and individual eggs are easily seen. The palps of adult males are very large and conspicuous. Web structure varies considerably within the family. Huber (2005) notes that the taxonomy of Nearctic pholcids is greatly in need of revision (this is presumably true for other regions as well). Much progress has been made, however, in understanding the higher level systematics and biogeography of the pholcids (Huber 2011; Dimitrov et al. 2013 and references therein). References cited in Dimitrov et al. (2013) provide an excellent entry into the pholcid literature.

Comprehensive Description

    Pholcidae
    provided by wikipedia
    For other arthropods called "daddy longlegs", see Daddy longlegs.

    Pholcidae, commonly known as cellar spiders, are a spider family in the suborder Araneomorphae. The family contains about 1500 species divided into about 80 genera.

    Some species, especially Pholcus phalangioides, are commonly called daddy long-legs spider, granddaddy long-legs spider, carpenter spider, daddy long-legger, or vibrating spider. Confusion often arises because the name "daddy long-legs" is also applied to two distantly related arthropod groups: harvestmen (which are arachnids but not spiders) and crane flies (which are insects).

    Appearance

    Pholcids are thin and fragile arachnids. The body (resembling the shape of a peanut) being approximately 2–10 mm (0.08-0.39 in) in length with legs which may be up to 50 mm (1.97 in) long. Pholcus and Smeringopus have cylindrical abdomens and eyes arranged in two lateral groups of three and two smaller median contiguous eyes. Arrangements of eight and six eyes both occur in this family. Spermophora has a small globose abdomen and its eyes are arranged in two groups of three without median eyes. Pholcids are gray to brown, sometimes clear, with banding or chevron markings.

    Habitat

    Pholcids are found in every continent in the world except Antarctica. Pholcids hang inverted in their messy and irregular-shaped webs. These webs are constructed in dark and damp recesses such as caves, under rocks and loose bark, abandoned mammal burrows. In areas of human habitation pholcids construct webs in undisturbed areas in buildings such as attics and cellars (hence the common name "cellar spider").[3]

    Behavior

    Cellar spider vibrating rapidly in response to a threat

    Trapping

    The web of pholcids has no adhesive properties and instead relies on its irregular structure to trap prey. When pholcid spiders detect prey within their webs the spiders quickly envelop prey before inflicting a fatal bite. The prey may be eaten immediately or stored for later. When finished they will "clean" the web by unhooking the prey and letting it drop from the web.

    Threat response

    Some species of Pholcidae exibit a threat response when disturbed by a touch to the web or entangled large prey. The arachnid responds by vibrating rapidly in a gyrating motion in its web. While they are not the only species of spider to exhibit this behaviour, this behaviour has led to these spiders sometimes being called "vibrating spiders". There are several proposed reasons for this threat response. The movement may make it difficult for a predator to locate the spider or may be a signal to an assumed rival to leave. Vibrating may also increase the chances of capturing insects that have just brushed their web and are still hovering nearby.[4] If the spider continues to be harassed it will retreat into a corner or drop from its web and escape.

    Diet

    Certain species of these spiders invade webs of other spiders to eat the host, the eggs, or the prey. In some cases the spider vibrates the web of other spiders, mimicking the struggle of trapped prey to lure the host closer. Pholcids are natural predators of the Tegenaria species and are known to attack and eat redback spiders, huntsman spiders and house spiders.[5][6] Pholcids may be beneficial to humans living in regions with dense hobo spider populations as predation on Tegenaria may keep populations in check.[7]

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    Close-up of a cellar spider's head, showing two groups of three closely clustered eyes

    Gait

    Pholcus phalangioides often uses an alternating tetrapod gait (first right leg, then second left leg, then third right leg, etc.), which is commonly found in many spider species. However, frequent variations from this pattern have been documented during observations of the spiders’ movements.

    Systematics

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    Two Crossopriza lyoni. The bottom one is male. The female is clutching her egg bundle (magnified).
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    Smeringopus pallidus female with egg sac.
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    A cellar spider stays close to her young in Tulare, California.
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    A marbled cellar spider (Holocnemus pluchei) carrying prey.
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    Male shortbodied cellar spider (Spermophora senoculata) from the United States

    As of November 2015[update], the World Spider Catalog accepts the following genera:[1]

    Misconceptions

    There is a legend that daddy long-legs spiders have the most potent venom of any spider, but that their fangs are either too small or too weak to puncture human skin; the same legend is also repeated of the harvestman and crane fly, also known as "daddy long-legs" in some regions. Indeed, pholcid spiders do have a short fang structure (called uncate due to its "hooked" shape). Brown recluse spiders also have uncate fang structure, but are able to deliver medically significant bites. Possible explanations include: pholcid venom is not toxic to humans; pholcid uncate are smaller than those of brown recluse; or there is a musculature difference between the two arachnids, with recluses, being hunting spiders, possessing stronger muscles for fang penetration.[8]

    During 2004, the Discovery Channel television show MythBusters tested the daddy long-legs venom myth in episode 13 - "Buried in concrete". Hosts Jamie Hyneman and Adam Savage first established that the spider's venom was not as toxic as other venoms, after being told about an experiment whereby mice were injected with venom from both a daddy long-legs and a black widow, with the black widow venom producing a much stronger reaction. After measuring the spider's fangs at approximately 0.25 mm, Adam Savage inserted his hand into a container with several daddy-long-legs, and reported that he felt a bite which produced a mild, short-lived burning sensation. The bite did in fact penetrate his skin, but did not cause any notable harm.[9] Additionally, recent research has shown that pholcid venom is relatively weak in its effects on insects.[10]

    According to Rick Vetter of the University of California at Riverside, the daddy long-legs spider has never harmed a human and there is no evidence that they are dangerous to humans.[11]

    The legend may result from the fact that the daddy long-legs spider preys upon deadly venomous spiders, such as the redback, a member of the black widow genus Latrodectus.[12] To the extent that such entomological information was known to the general public, it was perhaps thought that if the daddy long-legs spider could kill a spider capable of delivering fatal bites to humans, then it must be more venomous, and the uncate fangs were regarded as prohibiting it from killing people. In reality, it is able to cast lengths of silk onto its prey, incapacitating them from a safe distance.[13]

    References

    Notes

    1. ^ a b "Family: Pholcidae C. L. Koch, 1850 (genus list)", World Spider Catalog, Natural History Museum Bern, retrieved 2015-11-10.mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
    2. ^ "Currently valid spider genera and species", World Spider Catalog, Natural History Museum Bern, retrieved 2015-11-10
    3. ^ Web, Animal Diversity. "BioKIDS - Kids' Inquiry of Diverse Species, Pholcidae: INFORMATION". www.biokids.umich.edu. Retrieved 2018-07-15.
    4. ^ Bruce Marlin (2006-04-25). "Video of the "vibrating spider" vibrating" (QuickTime Movie).
    5. ^ "Daddy Long Legs". Queensland Museum.
    6. ^ Wim van Egmond. "Pholcus phalangioides, the daddy-long-legs spider, in 3D".
    7. ^ "Pholcus phalangioides (Long-bodied Cellar Spider) - Spider Identification & Pictures". spiderid.com. Retrieved 2018-07-15.
    8. ^ "Daddy Long Legs Site on UCR".
    9. ^ "Myth Files on the Discovery site". Discovery channel.
    10. ^ "The Spider Myths Site". Burke Museum. 2005-05-12.
    11. ^ Spider Myths-DaddyLongLegs
    12. ^ "FAMILY PHOLCIDAE – Daddy long-leg Spiders". Brisbane Insects and Spiders: The Expression of our Love of Nature. 2009. Retrieved 2009-11-13.
    13. ^ http://www.tepapa.govt.nz/researchattepapa/enquiries/spidersweb/what/pages/daddylonglegs.aspx

    Bibliography

    • Pinto-da-Rocha, R., Machado, G. & Giribet, G (eds.) (2007) Harvestmen – The Biology of Opiliones. Harvard University Press ISBN 0-674-02343-9