Pholcus phalangioides

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Geographic Range

Pholcus phalangioides is found throughout the world. It is a common cellar spider throughout the United States. (Emerton, 1902; Jackman, 1997)

Habitat

Pholcus phalangiodes can be found in undisturbed, low light locations. Some places one might encounter this spider are in basements, under stones, under ledges, and in caves. People most often associate these spiders with living on ceilings and in corners in homes. They make their webs large, loose, and flat, but they can make them in irregular shapes to fit into surrounding objects. Their webs are normally oriented horizontally. Pholcus phalangioides hangs upside down on the web it makes. (Emerton, 1902; Foelix, 1982; Jackman, 1997; Uhl, November 1998)

Physical Description

Pholcus phalangioides is pale yellow-brown except for a large gray patch in the center of the cephalothorax. The body and legs are almost translucent. These spiders are covered with fine gray hairs. The head is a darker color around the eyes. A translucent line marks the dorsal vessel. There are eight eyes: two small eyes in front of the two triads of larger eyes.

Females are seven to eight millimeters in length and males are six millimeters.

Because of the translucent quality of this animal, using a microscope it is possible to see the moving blood cells in the legs and body of a living animal. (Jackman, 1997)

  • Sexual Dimorphism
  • female larger
  • Range length
    6 to 8 mm
    0.24 to 0.31 in

Development

A mother P. phalangioides watches over her newly hatched young (prenymphs) for about nine days until the prenymphs shed their skins to become little spiders. The young spiders then leave the maternal web, and go look for a place to build their own webs. (Stüber, 1999)

Reproduction

In studies done by Gabriele Uhl at the University of Bonn, male P. phalangioides seemed to be attracted to and to mate with larger females more often than smaller females. This may increase reproductive success for males, because large females produce more eggs than smaller females. (Uhl, November 1998)

Before mating, a male spider deposits some sperm onto a little web, and then sucks it into a special cavity within his pedipalp. During mating, which can take several hours, the male deposits his sperm into the female's epigynum, which is an opening on the underside of her abdomen. Females can store the sperm in a special cavity at the beginning of the uterus, called the uterus externus, until it is time for her eggs to be fertilized. Timing of fertilization and laying depends on the availability of food. Because the sperm are stored for some period of time, it is possible for a female to mate again. If this occurs, the sperm from the two males mixes in the uterus externa. However, the sperm of the last male mated with has priority in fertilizing the eggs. This is because of a mechanism of sperm removal during mating. Males perform rhythmic movements of their intromittent organs during copulation, which results in extrusion of most of the sperm already in the uterus externa.

After a female lays her eggs, she wraps them in silk strands and carries the package in her chelicera (jaws), located on the underside of her body. (Emerton, 1902; Jackman, 1997; Stüber, 1999; Uhl, November 1998)

  • Breeding season
    Peak breeding occurs between June and September.

The only parental care female P. phalangioides offer their young is nine days of protection as the prenymphs finish developing into spiders. (Stüber, 1999)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • protecting
      • female

Lifespan/Longevity

Pholcus phalangioides can live up to about three years. (Stüber, 1999)

  • Range lifespan
    Status: wild
    3 (high) years
  • Range lifespan
    Status: captivity
    3 (high) years

Behavior

When P. phalangioides is not mating, it is a solitary creature that work on catching food in its web. (Uhl, November 1998)

Communication and Perception

Male spiders find a female spiders by tracking the pheromones she leaves. During mating, tactile communication is probably of some importance. (Jackman, 1997)

Food Habits

Pholcus phalangioides seems to prefer other spiders and small insects as prey. Also, males and females have both been known to engage in cannibalism. Females have been seen invading another spider's web, eating that spider, and using the foreign web to catch new prey for themselves. These spiders kill and digest their prey using venom. (Jackman, 1997; Stüber, 1999; Uhl, November 1998)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

When the web of P. phalangioides is disturbed, the spider swings its body around rapidly with its legs attached firmly to its web. It swings fast enough that the spider becomes very hard to see. This may be a form of camouflage. (Emerton, 1902; Stüber, 1999)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • Birds

Ecosystem Roles

Because their diet is primarily insects, these spiders play the important role of controlling the growth of insect populations. (Stüber, 1999)

Economic Importance for Humans: Positive

Pholcus phalangioides helps control pest populations. (Uhl, November 1998)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

These spiders often live inside houses, where humans do not normally want spiders and their webs. (Uhl, November 1998)

  • Negative Impacts
  • household pest

Conservation Status

At this time Pholcus phalangioides are not endangered or threatened, so there is no conservation underway (ESA).

Other Comments

Because one of the common names for Pholcus phalangioides is daddylongleg spider, it is often confused with the Harvestmen daddylong legs, which are a separate species that is not even a true spider. Also, despite the urban myth that the daddylongleg spider is the most poisonous spider in the world, there is no proof for this statement. It is thought that this rumor may have been started because P. phalangioides kill and eat other spiders, including the Redback Spiders, whose venom can be fatal to humans. But to be able to kill the Redback spider, the P. phalangioides need only to have a quicker bite, not be more venomous (Crew, Haudon).

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Anna Ferrick (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

motile

having the capacity to move from one place to another.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

References

Emerton, J. 1902. The Common Spiders of the United Stateds. Boston, U.S.A., and London: Ginn & Company, Publishers.

Foelix, R. 1982. Biology of Spiders. Cambridge, Massachusets, and London, England: Harvard University Press.

Jackman, J. 1997. A Field Guide ot Spiders & Scorpions of Texas. Houston, TX: Gulf Publishing Company.

Stüber, K. 1999. "Biology of *Pholcus phalangioides*" (On-line). Accessed October 2, 2001 at http://caliban.mpiz-koeln.mpg.de/~stueber/essays/pholcus/pholcus_phalangioides.html.

Uhl, G. November 1998. Mating Behavior in the Cellar Spider, Pholcus phalangioides. Animal Behavior, Volume 56 Issue 5: 1155-1159.