Probably one of the spider genera best known to humans is the pholcid genus Pholcus. Commonly known as daddy-longlegs or cellar spiders, many species from this genus are synanthropic and often share our houses with us. Daddy-longlegs are even important characters in children's tales such as The Tale of Daddy-longlegs by Scott Arthur Bailey. However in some places "daddy-longlegs" is used when referring to harvestmen (Opiliones).
Pholcids show very high ecological plasticity and can be found everywhere, from deserts to humid tropical forests. Similar to many other arthropod groups the pholcids are most diverse in the tropical regions of the world. Several studies have shown that pholcids might be among the commonest if not the dominating web builders in some tropical regions (Manhart, 1994; Huber, 2000, 2003a). Currently there are 85 genera and 1000 species (Platnick, 2009) of pholcids but recent evidence shows that most of the diversity of this group is still unknown (Huber, 2000, 2003a, 2003b, 2003c, 2005a, 2005b, 2007).
Pholcidae C. L. Koch, 1850
Pholcidae C. L. Koch, 1850
Most pholcids are relatively small spiders with rounded prosoma and legs that usually are disproportionately long in relation to their body size. In some species legs may be over 20 times the body length of the animal. However, many leaf litter species have quite short legs. Pholcids are very variable in body shape and coloration but there are several diagnostic characters that distinguish them from other relatives. The most important are: the modified male palpal paracymbium called procursus, the sexual modifications of the male chelicerae and the pseudosegmentation of the leg tarsi.
Left: Prosoma of Pholcus edentatus frontal. Note the hornlike elevations on which lateral eye triads are placed. Center: Leg IV tarsus of Pholcus edentatus. Right: Male pedipalp of Pholcus ornatus. Note the conspicuously enlarged and modified paracymbium (procursus). Images © 2005 Dimitar Dimitrov
Pholcids have eight or six eyes. Eyes are arranged in two lateral triads and the anterior median eyes are placed in between, on the frontal part of the prosoma. In six-eyed species the anterior median eyes are absent. In some genera eyes are placed on conspicuous elevations of the prosoma. These often resemble a pair of horns, each one carrying one of the lateral eye triads. In many cave dwelling species eyes are further reduced in number and size and in many troglobite species eyes are completely lost.
The vast majority of pholcids build webs which vary greatly in size and complexity. Many species construct irregular three-dimensional webs but more ordered sheet webs are also no exception.
Reproductive biology in pholcids and functional morphology of their genitalia is fairly well studied (e.g., Gerhardt, 1921, 1923, 1924, 1927, 1929; Uhl et al., 1995; Eberhard and Briceño, 1983, 1985; Huber, 1994, 1995, 1997a, 1997b, 1998, 2002; 2004, 2006; Huber and Eberhard, 1997). Pholcids have a fairly complex courtship behavior and numerous male structures besides the pedipalps, such as modified cheliceral hairs and/or apophysis and in some cases even apophyses on the clypeus, are involved in the copulation.
Pholcids lay few eggs, in some cases less than 10. Females do not make cocoons but carry the eggs in their jaws. Often, maternal care continues for some time after the spiderlings have hatched. Spiderlings have shorter legs in relation to their body size than adults, but after several molts leg-to-body-size proportion changes.
There are hundreds of species of cellar spiders found all over the world. One species in particular, Pholcus phalangioides, is particularly comfortable living in houses and other buildings, and so has been spread all around the world by people moving around. Only a few species occur in Michigan, but they are common in basements and unused buildings.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native )
Like all spiders, cellar spiders have two body-segments, a cephalothorax in front and an abdomen behind. They have eight legs, all attached to the cephalothorax. Cellar spiders have very long thin legs compared to other spiders. Their legs are many times longer than their bodies. Because of this they are sometimes called "daddy longlegs spiders", though they are not related to the other "daddy longlegs," which are Harvestmen. On the front they have two small "mini-legs" called palps. These are used to grab prey, and in mating, and are much bigger in male spiders than in females.
Different species of cellar spiders have six or eight eyes, and the size and arrangement of eyes is different in different groups. Cellar spiders have fangs that they use to bite their prey with, and have venom glands, but their fangs are very short. Their color varies from light tan to grayish-brown.
Female cellar spiders are often much bigger than males.
Range length: 2.0 to 10.0 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; venomous
Sexual Dimorphism: sexes alike; female larger
These spiders prefer to live in dark places: in caves, cracks and crevices in rocks, unused animal burrows, and in the dark and quiet parts of buildings.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: taiga ; chaparral ; forest ; rainforest ; scrub forest ; mountains
Like all spiders, cellar spiders are predators. They eat Insecta, Araneae, and other small invertebrates. They spin a large loose, three-dimensional web (not flat like orbweavers) that is not sticky. They use their web as a kind of prey-detection system. When a passing insect bumps into it, they come running out and grab it and bite it, then wrap it in silk. Formicidae are particularly common prey.
Many cellar spiders also raid the webs of other spiders, eating their prey and the spiders themselves. They sometimes hunt around the edges of the webs of female spiders of other species. Males who come to mate with the female may get eaten by the cellar spider instead.
Cellar spiders mainly avoid predators by living in dark places. If their web is touched, they sometimes vibrate back and forth very fast. We don't know for sure why they do this, maybe to make themselves harder to see.
- other Araneae
- small Squamata
- small mammals especially Soricidae
Life History and Behavior
Communication and Perception
Spiders in this group probably use touch and chemicals to communicate, though they can see too. They are also very sensitive to vibrations in their webs.
Cellar spiders hatch from eggs, and the hatchlings look more or less like grown-up spiders, though sometimes their colors change as they age. To grow they have to shed their exoskeleton, which they do many times during their lives.
We don't know for sure how long these spiders live, probably only a few years at most, and very few probably make it that long.
Not much is known about reproduction in this group of spiders.
Breeding season: unknown
Key Reproductive Features: sexual ; fertilization (Internal ); oviparous
Female cellar spiders form their eggs into a ball. They hold the ball in their jaws for several weeks while the eggs develop, and when they new spiders hatch, they ride on their mother for several days before dispersing.
Parental Investment: female parental care
Evolution and Systematics
Discussion of Phylogenetic Relationships
Despite important advances in recent years (Huber, 2000; Bruvo-Madaric et al., 2005) the family level phylogeny of pholcids is still a work in progress. Several subfamilies of pholcids have been named but their limits remain elusive. The phylogenetic hypothesis illustrated above is derived from the only family-wide phylogenetic study that includes molecular and morphological data (Bruvo-Madaric et al., 2005).
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:715
Specimens with Barcodes:515
Species With Barcodes:179
No cellar spider species are known to be endangered.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Positive
These spiders are not dangerous to people, and they sometimes eat insects that are pests to humans.
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: the harvestmen (which are arachnids but not spiders), and crane flies (which are insects).
Pholcids are fragile arachnids, 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 eyes. 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 and no median eyes. Pholcids are gray to brown with banding or chevron markings. The shape of the Pholcus and Smeringopus's body resembles that of a peanut.
Pholcids are found in every continent in the world except Antarctica where it is too cold for them to survive. They hang inverted in messy, irregular, tangled webs. These webs are constructed in dark and damp recesses, such as: caves, under rocks and loose bark, abandoned mammal burrows, and undisturbed areas in buildings, such as cellars (hence the common name "cellar spider"). However, Pholcids are also quite commonly found in warm, dry places, such as household windows and attics.
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 the arachnid 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 and difficult to focus on. For this reason pholcids have sometimes been called "vibrating spiders", although they are not the only species to exhibit this behavior. Doing so might make it difficult for a predator to see exactly where the spider is, may be intended to signal an assumed rival to leave, or may increase the chances of capturing insects that have just brushed their web and are still hovering nearby. If the spider continues to be harassed it will retreat into a corner or drop from its web and escape.
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.
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.
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
- Modisiminae (New World group)
- 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
- Ninetinae (not monophyletic)
- 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
- Pholcinae C. L. Koch, 1851
- 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
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 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 (average human skin thickness varies from about 0.5 mm to 4 mm), Adam Savage allowed himself to be bitten, and reported that the bite produced little more than a mild short-lived burning sensation. This appears to confirm that, contrary to popular belief, pholcid bites can penetrate human skin but will deliver a harmless envenomation. Additionally, recent research by Alan Van Dyke has shown that pholcid venom is relatively weak in its effects on insects as well.
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.
The urban legend ostensibly stems from the fact that the daddy long-legs spider is known to prey upon deadly venomous spiders, such as the redback, a member of the black widow genus Latrodectus. By extrapolation, it was thought that if the daddy long-legs spider could regularly kill a spider capable of delivering fatal bites to humans, then it must be more venomous, and the uncate fangs were accused of prohibiting it from killing people. In reality, it is able to cast lengths of silk onto its prey, incapacitating them from a safe distance.
- Bruce Marlin (2006-04-25). "Video of the "vibrating spider" vibrating" (QuickTime Movie).
- "Daddy Long Legs". Queensland Museum.
- Wim van Egmond. "Pholcus phalangioides, the daddy-long-legs spider, in 3D".
- Joel Hallan (2005-03-07). "Synopsis of the described Araneae of the world". Texas A&M University.
- "Daddy Long Legs Site on UCR".
- "Myth Files on the Discovery site". Discovery channel.
- "The Spider Myths Site". Burke Museum. 2005-05-12.
- Spider Myths-DaddyLongLegs
- "FAMILY PHOLCIDAE – Daddy long-leg Spiders". Brisbane Insects and Spiders: The Expression of our Love of Nature. 2009. Retrieved 2009-11-13.
- "How to Kill a Venomous Spider". wikiHow. Retrieved 2009-11-13.
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