Tetragnathidae

Menge, 1866

Long-jawed Orb Weavers, Long-jawed Orbweavers

Genus Guides

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Long-jawed orb weavers are a of spiders characterized by elongated bodies, long legs, and often extraordinarily long (jaws). Most construct orb webs in a horizontal or near-horizontal plane, distinguishing them from the vertical webs typical of Araneidae. The family includes diverse ecological : meadow-dwelling species that camouflage as grass stems, riparian species that build webs over water, and cave-dwelling species adapted to dimly lit environments. Some species exhibit social , forming communal webs spanning extensive areas.

Pachygnatha furcillata by (c) Nathan T. Jones, some rights reserved (CC BY), uploaded by Nathan T. Jones. Used under a CC-BY license.Tetragnatha nitens by (c) Robert Whyte, some rights reserved (CC BY). Used under a CC-BY license.Tetragnatha nitens by (c) Julien Tchilinguirian, some rights reserved (CC BY), uploaded by Julien Tchilinguirian. Used under a CC-BY license.

Pronunciation

How to pronounce Tetragnathidae: //ˌtɛtrəɡˈnæθɪˌdiː//

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Identification

Distinguished from Araneidae by horizontal (rather than vertical) web orientation in most . Many species have elongated bodies with long legs held close together, creating a stick-like silhouette. and fangs are often conspicuously elongated, especially in males. Cave-dwelling Meta species lack the exaggerated jaws and elongated body typical of the . Spiny legs separate Tetragnathidae from similar-looking Theridiidae and Linyphiidae.

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Habitat

Highly variable: meadows and fields for smaller ; riparian corridors, ponds, and streams for larger species; caves, abandoned mines, wells, basements, and shaded ravines for troglophilic species. Horizontal webs are typically anchored to vegetation or built from ceilings in cave environments. Some species occupy the web hub, others sit on the periphery hugging substrate.

Distribution

distribution with fifteen of Tetragnatha across North America. Meta ovalis ranges from southeast Canada to Georgia and west to the Mississippi River, especially along the Appalachian Mountains and Ozark Plateau. Tetragnatha guatemalensis found from southern U.S. through Central America. Leucauge species common in eastern U.S. and southeastern Mexico.

Seasonality

Most abundant in summer. Mature individuals of meadow found spring through fall; some active year-round in Florida. Tetragnatha praedonia exhibits multivoltine with spiderling June-September and multiple overlapping per year.

Diet

Primarily aerial insects: Diptera (especially , gnats, mosquitoes), mayflies, and other small flying insects. Larger prey including Lepidoptera, craneflies, , grasshoppers, ants, and stinkbugs captured by some . Tetragnatha praedonia specializes on midge flies smaller than 3mm.

Life Cycle

Females deposit in silken sacs attached to twigs, substrate, or suspended on web periphery. Egg sac appearance varies by . Tetragnatha praedonia: newly hatched spiderlings emerge repeatedly June-September; males develop in 57-59 days, females in 47-51 days. Multiple per year with generation overlap in multivoltine species.

Behavior

Web-building varies: most construct horizontal orbs with widely spaced spirals; Meta ovalis builds vertical webs. Many sit at web hub or periphery, adopting camouflage posture with legs drawn together to resemble plant stems. When disturbed, dash from web to hug grass stalks. Some species tolerate close proximity to conspecifics; Tetragnatha guatemalensis forms communal webs spanning acres. Males use elongated legs in . During mating, both sexes grasp each other's jaws; males may possess cheliceral spurs to receive female fangs.

Ecological Role

Important of flying insects including pest such as mosquitoes and midges. Contribute to regulation of aquatic insect in riparian . Serve as prey for larger arthropods and vertebrates. Cave-dwelling species may function as for fungi transfer to other cave arthropods.

Human Relevance

Generally harmless to humans; not dangerously venomous. Golden silk spider (Trichonephila clavipes) produces exceptionally strong silk studied for biomaterial applications. Some abundant in agricultural settings including cocoa agroecosystems, potentially contributing to pest control. Cave species of conservation interest due to limited distributions and specificity.

Similar Taxa

  • AraneidaeAlso build orb webs, but typically orient webs vertically rather than horizontally; lack the elongated body and exaggerated of most Tetragnathidae.
  • Philodromidae (slender crab spiders)Similar elongated body and camouflage posture on vegetation, but do not build webs for prey capture; legs arranged laterally like crabs rather than held close together.
  • Linyphiidae (sheetweb weavers)May be confused with cave-dwelling Meta , but build flat sheet webs rather than orbs; lack spiny legs present in Tetragnathidae.
  • Theridiidae (cobweb weavers)Some build irregular webs in similar , but lack spiny legs and have rounded ; web architecture differs fundamentally.

More Details

Social behavior

Tetragnatha guatemalensis exhibits essentially social , forming communal webs that can stretch for acres. This was responsible for the famous 2007 mass webbing event at Lake Tawakoni State Park, Texas.

Troglophilic adaptations

Meta ovalis is classified as a troglophile rather than troglobite: it occupies cave entrances and twilight zones, retains full pigmentation and functional , and does not penetrate deep recesses. specimens may occur deeper in caves and construct larger webs to compensate for scarce prey.

Predatory strategy evolution

Tetragnatha praedonia exhibits intermediate evolutionary stage in predatory : retains primitive "seize-pull out" strategy for small prey while capable of advanced "bite-wrap" and "wrap-bite" strategies used by Araneidae for larger or dangerous prey.

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Sources and further reading