Long-Jawed Orb Weaver

Tetragnatha sp.
Wednesday, June 22, 2011

This odd-looking spider is a member of the Long-Jawed Orb Weaver group, so named because of their abnormally large jaws and the shape of the webs which they build.

            These spiders are immediately recognizable from their thin, elongated body and their very long legs (up to a 5 cm leg span). They also possess massive chelicerae, or jaws, which are projected forward from their body. These can, in some cases, exceed the length of their cephalothorax (head). The body coloration within this genus, or even within individual species, is highly variable. Like all other spiders, they possess eight eyes and eight legs. 

           

As the latter part of their common name suggests, these spiders build orb-shaped webs. As in the diagram to the right, these webs are constructed with a “wagon wheel” design: dry, non-sticky threads form 12-20 “spokes,” while a sticky spiral of adhesive silk fills in the web. However, the diagram to the right is an example of the orb webs typically woven by spiders from the family Araneidae (Orb-Weaver Spiders). Long-Jawed Orb Weavers, in the related family Tetragnathidae, generally leave an opening in the middle of their orb web. That is one important way that their webs can be distinguished from their non-long-jawed relatives. Spiders from the genus Tetragnatha also typically build their webs on a horizontal incline. They are usually 20 cm in diameter.

            Long-Jawed Orb Weavers build loose orb webs, which are taken down and reconstructed often. They build these webs on horizontal inclines, generally on low vegetation near wetlands or bodies of water. These spiders sit in their web or on a nearby plant and wait for prey to tangle itself in the web. They generally eat small flying insects, including moths and leafhoppers. When their longer legs are stretched flat, these spiders camouflage themselves well against a twig or a plant stem. Despite that, they are predated by birds and other small animals. In addition to constructing webs in vegetation, these spiders are known to be able to walk on water.    

            Near the end of summer, Long-Jawed Orb Weavers mate and the female will lay eggs before she dies. The next spring, young spiders emerge as miniature versions of their adult selves. As they grow, they shed their skin, or cuticle, frequently. They do not typically outlive one year of age.

            This specimen is a female, distinguishable by her larger size (12 mm excluding legs). She was found floating in the Mountain Lake Pond, apparently dead.

Article by Hazel Galloway

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