Tetragnatha Spider

This relatively common garden dwelling spider is a long-jawed orb-weaver Tetragnatha species. Long-jawed orb weavers belong to the family Tetragnathidae. I have used Canon EOS 5DSR with Canon EF 100mm f/2.8L Macro IS USM using 36mm Kenko extension tube. This whole setup is illuminated by Canon MT-24EX macro twin light flash.

They were first described in 1804, by Pierre André Latreille and their name is derived from the Greek word tetra, meaning ‘four’ and gnathos, meaning ‘jaw’. Many species possess extraordinarily elongated jaws and fangs, with the body being almost twig like, with long, stick like legs. The narrow shape, when combined with their resting posture, helps camouflage them, even if they are sitting right in the middle of their webs.

The spider family Tetragnathidae also includes two types of spiders that are closely related but look very different: the common Long-Jawed Orb Weavers, we discussed earlier and the Orchard Spiders.

Orchard Spiders also possess long fangs, but their bodies are not as elongated and skinny looking, as their long-jawed cousins. In fact, orchard spiders look awfully similar to the ‘true’ orb-spiders (family Araneidae), until you get a closer look at the long fangs and were, not too long ago, classified together in the same family.

Like true orb-weavers, long-jawed orb-weavers and orchard spiders build webs that resemble a circular grid, however, their webs usually do not possess as many radii, or “spokes,” as those of true orb weavers.

Long-jawed orb weavers construct orb webs in a horizontal plane, or close to it. This helps differentiate their webs from the vast majority of orb weavers that create webs on a vertical axis.

They are quite tolerant of their brethren, too, often building individual webs in close proximity to each other. This behavior reaches its zenith in Tetragnatha guatemalensis. The species is, for all means and purposes, essentially social, and capable of spinning communal webs that can stretch for acres.

Those species that spin their webs in meadows and glades, usually occupy the hub of their webs, but their long bodies, complemented by long legs held close to their bodies, when at rest, allow them to pass off as broken bits of grass and other debris. Additionally, many species are straw-colored, and seem to blend in quite well. When disturbed, they make a dash from their webs, hugging their bodies to grass stalks or twigs, blending in almost imperceptibly with the background. You can see that behavior in the picture below when it got disturbed by my movement.

Water-loving species often prefer sit on the perimeter of their webs, once again resting close to the substrate, often a twig or piece of emergent vegetation that anchors one corner of their web. Their orbs usually have the spiral widely spaced, and yet the snare is equally effective in trapping aquatic insects such as midges, gnats, mosquitoes and mayflies that emerge directly from the water into the air, the horizontal web intercepting their flight, on the way up.

Adult tetragnathids, depending upon the species, can range from 5-16 mm or so, in body length, their long, spindly legs making them appear even longer.

Males are usually slightly smaller in length, as is the case with the vast majority of the Aranea (Spiders). During mating, both sexes grasp each other’s jaws. Males may have spurs on the chelicerae to receive the female’s fangs, presumably to avoid fatal results, from the whole affair.

Females deposit their eggs in silken egg sacs, which vary in appearance, depending upon species. Some are adhered closely to a twig or other such object, blending in with the substrate.

Identifying long-jawed orb weavers to species is an inexact science, based in large part on the structure of their genitalia; and also on the relative spacing of the eyes, and the length of the jaws relative to the length of the carapace (top of the cephalothorax).

That being said, long-jawed orb weavers certainly deserve our gratitude, for their role in helping diminish, the ever burgeoning populations of mosquitoes, midges, gnats and flies and other insect pests, plaguing humanity since centuries ago.

Thanks to my associate and arachnologist Javed Ahmed, for helping me to write this article.