Agelenidae

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The Agelenidae are a large family of spiders in the suborder Araneomorphae. Well-known examples include the common "grass spiders" of the genus Agelenopsis. The most widely accepted common name for members of the family is funnel weaver.<ref name="BEA" />

Description

The body length of the smallest Agelenidae spiders is about Template:Convert, excluding the legs, while the larger species grow to Template:Convert long. Some exceptionally large species, such as Eratigena atrica, may reach Template:Convert in total leg span.

Agelenids have eight eyes in two horizontal rows of four. Their cephalothoraces narrow somewhat towards the front where the eyes are. Their abdomens are more or less oval, usually patterned with two rows of lines and spots. Some species have longitudinal lines on the dorsal surface of the cephalothorax, whereas other species do not; for example, the hobo spider does not, which assists in informally distinguishing it from similar-looking species.<ref name="VAHI" />

Biology

File:Labyrinth spider (Agelena labyrinthica) female in web funnel.jpg
Female Agelena labyrinthica in her web funnel in Belgium.

Most of the Agelenidae are very fast runners, especially on their webs. With speeds clocked at Template:Convert, the giant house spider held the Guinness Book of World Records title for top spider speed until 1987. A recent literature review found peer-reviewed accounts of several agelenid species achieving speeds in this range, though some other taxa have achieved higher speeds.<ref name="spagna" /><ref name="barth" />

Agelenids build a flat sheet of nonsticky web with a funnel-shaped retreat to one side or occasionally in the middle, depending on the situation and species. Accordingly, "funnel weaver" is the most widely accepted common name for members of the family, but they should not be confused with the so-called "funnel-web tarantulas" or "funnel-web spiders" of mygalomorph families.<ref name="BEA"/>

File:Benoitia ocellata 309416034 558346569.jpg
male Benoitia ocellata from South Africa

The typical hunting mode for most sheet-building Agelenidae is similar to that of most other families of spiders that build sheet webs in the open, typically on grass or in scrubland as opposed to under bark, rocks, and the like. They await the arrival of prey such as grasshoppers that fall onto the horizontal web. Although the web is not sticky, it is full of entangling filaments that the spider continually lays down when passing over. The filaments catch in the least projections on a prey insect's body or limbs. The web also is springy, and whether perching on the sheet or awaiting prey in its retreat, the spider reacts immediately to vibrations, whether from a courting male, the threatening struggles of dangerous invaders, or the weaker struggles of potential meals. They attack promising prey by rushing out at high speed and dealing a paralysing venomous bite. The agatoxin in their venom has been studied extensively in Agelenopsis aperta.<ref name="adams" /> Once the prey has been disabled, the spider generally drags it back into the retreat and begins to feed. This method of attack is consistent with the high speeds at which the Agelenidae run. Other sheet-web hunters such as some Pisauridae also are very fast runners.

Like any fast-running spider, the Agelenidae possess good vision, and are generally photosensitive (i.e. react to changes in the light), so they can successfully retreat upon perceiving a larger threat's shadow approaching. Some are also sensitive to air currents caused by motion. Males are less successful ambushers than females and are more likely to roam to new territory in search of prey. In September, males of outdoors species (such as Agelenopsis and Agelena) may seek refuge within houses, usually nesting on or underneath outer windowsills, or around a porch door. These spiders often are neither pest controllers nor pests themselves; they are very selective in their prey and do not consume large quantities; also, they return to their webs after being disturbed, unless the web is completely destroyed.Template:Fact

Parasocial species

The type genus, Agelena, includes some parasocial spiders that live in complex communal webs in Africa. The best known of these is probably A. consociata. Social behaviour in these spiders comprises communal web-building, cooperative prey capture, and communal rearing of young. No trophallaxis occurs, though, nor does any true eusociality such as occurs in the social Hymenoptera (ants, bees, and wasps); for example, the spiders have no castes such as sterile workers or soldiers, and all females are reproductive.<ref name="Foelix2010" />

Genera

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Genera

Template:As of, this family includes 98 genera:<ref name="wsc" /> Template:Div col

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A number of fossil species are known from Eocene aged Baltic amber, but their exact relationship with extant members of the clade is unclear.<ref name="magalhaes" />

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See also

References

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Further reading

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