Pholcidae

Pholcidae

The Pholcidae are a spider family in the suborder Araneomorphae.

Some species, especially Pholcus phalangioides, are commonly called granddaddy long-legs spider, daddy long-legs spider, daddy long-legger, 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).

Appearance

Pholcids are fragile spiders, the body being 2–10 mm in length with legs which may be up to 30 mm long. Pholcus and Smeringopus have cylindrical abdomens and the eyes are arranged in two lateral groups of three and two smaller median contiguous eyes. Spermaphora has a small globose 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. 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 in undisturbed areas in buildings and cellars, hence the common name "cellar spiders".

Behavior

Trapping

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.

Threat Response

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 . If the spider continues to feel harassed it will retreat into a corner or drop from its web, and leave the harasser alone. When removed from their webs, pholcids are rather clumsy, and walk with an unsteady, bobbing action.

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 . 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 .

* Artema Walckenaer, 1837
* Aymaria Huber, 2000
* Cenemus Saaristo, 2001
* Ceratopholcus Spassky, 1934
* Crossopriza Simon, 1893
* Holocnemus Simon, 1873
* Hoplopholcus Kulczyn'ski, 1908
* Ixchela Huber, 2000
* Physocyclus Simon, 1893
* Priscula Simon, 1893
* Smeringopus Simon, 1890
* Stygopholcus Absolon & Kratochvíl, 1932
* Wugigarra Huber, 2001

* Blancoa Huber, 2000
* Bryantina Brignoli, 1985
* Canaima Huber, 2000
* Carapoia González-Sponga, 1998
* Chibchea Huber, 2000
* Coryssocnemis Simon, 1893
* Kaliana Huber, 2000
* Litoporus Simon, 1893
* Mecolaesthus Simon, 1893
* Mesabolivar González-Sponga, 1998
* Modisimus Simon, 1893
* Otavaloa Huber, 2000
* Pisaboa Huber, 2000
* Pomboa Huber, 2000
* Psilochorus Simon, 1893
* Stenosfemuraia González-Sponga, 1998
* Systenita Simon, 1893
* Tainonia Huber, 2000
* Teuia Huber, 2000
* Tupigea Huber, 2000
* Waunana Huber, 2000

* Aucana Huber, 2000
* Chisosa Huber, 2000
* Enetea Huber, 2000
* Galapa Huber, 2000
* Gertschiola Brignoli, 1981
* Guaranita Huber, 2000
* Ibotyporanga Mello-Leitão, 1944
* Kambiwa Huber, 2000
* Mystes Bristowe, 1938
* Nerudia Huber, 2000
* Ninetis Simon, 1890
* Nita Huber & El-Hennawy, 2007
* Papiamenta Huber, 2000
* Pholcophora Banks, 1896
* Tolteca Huber, 2000

* Aetana Huber, 2005
* Anansus Huber, 2007
* Anopsicus Chamberlin & Ivie, 1938
* Belisana Thorell, 1898
* Buitinga Huber, 2003
* Calapnita Simon, 1892
* Khorata Huber, 2005
* Leptopholcus Simon, 1893
* Metagonia Simon, 1893
* Micromerys Bradley, 1877
* Nyikoa Huber, 2007
* Ossinissa Dimitrov & Ribera, 2005
* Panjange Deeleman-Reinhold & Deeleman, 1983
* Paramicromerys Millot, 1946
* Pholcus Walckenaer, 1805
* Quamtana Huber, 2003
* Savarna Huber, 2005
* Smeringopina Kraus, 1957
* Spermophora Hentz, 1841
* Spermophorides Wunderlich, 1992
* Uthina Simon, 1893
* Wanniyala Huber & Benjamin, 2005
* Zatavua Huber, 2003

* Carupania González-Sponga, 2003
* Ciboneya Pérez, 2001
* Falconia González-Sponga, 2003
* Holocneminus Berland, 1942
* Micropholcus Deeleman-Reinhold & Prinsen, 1987
* Pehrforsskalia Deeleman-Reinhold & van Harten, 2001
* Pholciella Roewer, 1960
* Pholcoides Roewer, 1960
* 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 chelicerae (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 long-legs" 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.

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 varies from about 0.5mm to 4mm), 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 by Alan Van Dyke has shown that pholcid venom is actually relatively weak in its effects on insects as well.

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

One reason why these spiders are said to be so dangerous could be that they regularly prey on other spiders, including the black widow (Latrodectus spp.), which itself can be dangerous to humans, with the reasoning that the preying spider must be even more venomous; which is incorrect. (Pinto-da-Rocha et al. 2007:4)

Not spiders?

One rumor states that daddy long-legs spiders are not spiders. This rumor arises due to the multiple uses of the name daddy long-legs. The harvestman, which is called "daddy long-legs" in parts of the world, is an arachnid but not a spider. However the Pholcidae (daddy long-legs spider) is a true spider.

See also

References

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

External links

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