PHOLCIDAE

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

Contents

Appearance

Habitat

Diet

Systematics

Misconceptions

Most venomous?

Not spiders?

Gallery

See also

References

External links

Appearance

Pholcids are fragile spiders, the body being 2–10 mm in length with legs which may be up to 50 mm long. ''Pholcus'' and ''Smeringopus'' have cylindrical abdomens and the eyes are arranged in two lateral groups of three and two smaller median contiguous (together) eyes. ''Spermaphora'' has a small globose (round) abdomen and its eyes are arranged in two groups of three and no median eyes. Pholcids are gray to brown with banding or chevron markings. Curiously, the shape of the ''Pholcus'' and ''Smeringopus's body reflects that of a peanut shell.

Habitat

Pholcids are web-weaving spiders and are distributed worldwide. They hang inverted in messy, irregular, tangled webs. These webs are constructed in dark and damp recesses, in caves, under rocks and loose bark, abandoned mammal burrows and undisturbed areas in buildings and cellars, hence the common name "cellar spiders".
The web has no adhesive properties but the irregular structure traps insects, making escape difficult. The spider quickly envelops its prey with silk and then inflicts the fatal bite. The prey may be eaten immediately or stored for later. When removed from their webs, pholcids are rather clumsy, and walk with an unsteady, bobbing action.
When the spider is threatened by a touch to the web or when too large a prey becomes entangled, the spider vibrates rapidly in a gyrating motion in its web and becomes blurred, almost invisible. For this reason pholcids have sometimes been called "vibrating spiders", although they are not the only species to exhibit this behaviour. Doing so might make it difficult for a predator to see exactly where the spider is, or may increase the chances of capturing insects that have just brushed their web and are still hovering nearby ^[1]. If the spider continues to feel harassed it will retreat into a corner or drop from its web, and leave the harasser alone.

Diet

Certain species of these seemingly benign spiders invade webs of other spiders and 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 of the web closer. Pholcids are natural predators of the ''Tegenaria'' species, and are known to attack and eat redback spiders and huntsman spiders ^[2][3]. It is this competition that helps keep ''Tegenaria'' populations in check, which may be advantageous to humans who live in regions with dense hobo spider populations.

Systematics

For a complete list of the genera and species in this family, see List of Pholcidae species.
The categorization into subfamilies follows Joel Hallan's Biology Catalog ^[4].

★ Holocnemidae (probably not monophyletic)
:
★ ''Artema'' Walckenaer, 1837
:
★ ''Aymaria'' Huber, 2000
:
★ ''Cenemus'' Saaristo, 2001
:
★ ''Ceratopholcus'' Spassky, 1934
:
★ ''Crossopriza'' Simon, 1893
:
★ ''Holocnemus'' Simon, 1873
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★ ''Hoplopholcus'' Kulczyn'ski, 1908
:
★ ''Ixchela'' Huber, 2000
:
★ ''Physocyclus'' Simon, 1893
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★ ''Priscula'' Simon, 1893
:
★ ''Smeringopus'' Simon, 1890
:
★ ''Stygopholcus'' Absolon & Kratochvíl, 1932
:
★ ''Wugigarra'' Huber, 2001

★ Modisiminae (New World group)
:
★ ''Blancoa'' Huber, 2000
:
★ ''Bryantina'' Brignoli, 1985
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★ ''Canaima'' Huber, 2000
:
★ ''Carapoia'' González-Sponga, 1998
:
★ ''Chibchea'' Huber, 2000
:
★ ''Coryssocnemis'' Simon, 1893
:
★ ''Kaliana'' Huber, 2000
:
★ ''Litoporus'' Simon, 1893
:
★ ''Mecolaesthus'' Simon, 1893
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★ ''Mesabolivar'' González-Sponga, 1998
:
★ ''Modisimus'' Simon, 1893
:
★ ''Otavaloa'' Huber, 2000
:
★ ''Pisaboa'' Huber, 2000
:
★ ''Pomboa'' Huber, 2000
:
★ ''Psilochorus'' Simon, 1893
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★ ''Stenosfemuraia'' González-Sponga, 1998
:
★ ''Systenita'' Simon, 1893
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★ ''Tainonia'' Huber, 2000
:
★ ''Teuia'' Huber, 2000
:
★ ''Tupigea'' Huber, 2000
:
★ ''Waunana'' Huber, 2000

★ Ninetinae (not monophyletic)
:
★ ''Aucana'' Huber, 2000
:
★ ''Chisosa'' Huber, 2000
:
★ ''Enetea'' Huber, 2000
:
★ ''Galapa'' Huber, 2000
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★ ''Gertschiola'' Brignoli, 1981
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★ ''Guaranita'' Huber, 2000
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★ ''Ibotyporanga'' Mello-Leitão, 1944
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★ ''Kambiwa'' Huber, 2000
:
★ ''Mystes'' Bristowe, 1938
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★ ''Nerudia'' Huber, 2000
:
★ ''Ninetis'' Simon, 1890
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★ ''Papiamenta'' Huber, 2000
:
★ ''Pholcophora'' Banks, 1896
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★ ''Tolteca'' Huber, 2000

★ Pholcinae C. L. Koch, 1851
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★ ''Aetana'' Huber, 2005
:
★ ''Anopsicus'' Chamberlin & Ivie, 1938
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★ ''Belisana'' Thorell, 1898
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★ ''Buitinga'' Huber, 2003
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★ ''Calapnita'' Simon, 1892
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★ ''Khorata'' Huber, 2005
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★ ''Leptopholcus'' Simon, 1893
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★ ''Metagonia'' Simon, 1893
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★ ''Micromerys'' Bradley, 1877
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★ ''Ossinissa'' Dimitrov & Ribera, 2005
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★ ''Panjange'' Deeleman-Reinhold & Deeleman, 1983
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★ ''Paramicromerys'' Millot, 1946
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★ ''Pholcus'' Walckenaer, 1805
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★ ''Quamtana'' Huber, 2003
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★ ''Savarna'' Huber, 2005
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★ ''Smeringopina'' Kraus, 1957
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★ ''Spermophora'' Hentz, 1841
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★ ''Spermophorides'' Wunderlich, 1992
:
★ ''Uthina'' Simon, 1893
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★ ''Wanniyala'' Huber & Benjamin, 2005
:
★ ''Zatavua'' Huber, 2003

★ ''incertae sedis''
:
★ ''Carupania'' González-Sponga, 2003
:
★ ''Ciboneya'' Pérez, 2001
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★ ''Falconia'' González-Sponga, 2003
:
★ ''Holocneminus'' Berland, 1942
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★ ''Micropholcus'' Deeleman-Reinhold & Prinsen, 1987
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★ ''Pehrforsskalia'' Deeleman-Reinhold & van Harten, 2001
:
★ ''Pholciella'' Roewer, 1960
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★ ''Pholcoides'' Roewer, 1960
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★ ''Queliceria'' González-Sponga, 2003
:
★ ''Sanluisi'' González-Sponga, 2003
:
★ ''Tibetia'' Zhang, Zhu & Song, 2006
:
★ ''Trichocyclus'' Simon, 1908

Misconceptions

Most venomous?

There is an urban legend stating that daddy long-legs spiders have the most potent venom of any spider, but that their chelicera (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 called "daddy longlegs" in some locales. Indeed, pholcid spiders do have a short fang structure (called uncate). However, brown recluse spiders also have uncate fang structure, but are able to deliver medically significant bites. Either pholcid venom is not toxic to humans or there is a musculature difference between the two arachnids, with recluses, being hunting spiders, possessing stronger muscles for fang penetration.
Pholcid venom has never been scientifically tested on mammals. This would normally require milking the spiders and injecting the venom into humans or mice.
In 2004, the Discovery Channel show ''MythBusters'' set out to test the daddy long-legs myth (season 1, episode 13 ''"Buried in Concrete"''). After measuring the spider's fangs at approximately 0.25 mm (average human skin thickness is about 0.10 mm), the show's host was apparently bitten, although the bite produced little more than a mild short-lived burning sensation. This appears to confirm the suspicion that pholcids ''can'' penetrate human skin, but that their venom is practically harmless to humans. Additionally, recent research has shown that pholcid venom is actually relatively weak in its effects on insects as well^[5].
One reason why these spiders are said to be so dangerous could be that they regurarly prey on other spiders, including the black widow (''Latrodectus hasselti''), which itself can be dangerous to humans, with the reasoning that the preying spider must be even more venomous. (Pinto-da-Rocha ''et al.'' 2007:4)

Not spiders?

Another misconception is that the daddy long-legs spider is not a true spider. This misconception arises from the multiple uses of the name daddy long-legs. It is the harvestman (which is also called daddy long-legs) which is an arachnid but not a true spider. The daddy long-legs spider is a true spider.

Gallery

See also

★ Spider families

References

1. Video of the "vibrating spider" vibrating Bruce Marlin
2. Daddy Long Legs
3. ''Pholcus phalangioides'', the daddy-long-legs spider, in 3D Wim van Egmond
4. Synopsis of the described Araneae of the world Joel Hallan
5. The Spider Myths Site


★ , & (eds.) (2007): Harvestmen - The Biology of Opiliones. ''Harvard University Press'' ISBN 0-674-02343-9

External links

★ North American Spiders, Family Pholcidae Information and reference quality photos of cellar spiders. Includes quicktime movie of spiders "vibrating".

★ Good information and pictures of European Pholcidae