13 January 2009

Long-jawed Spider - Tetragnatha species

Click image to enlarge

Long-jawed Spider - Tetragnatha sp.

A strange looking spider with long needle-like fangs that are contained and protected by even longer chelicerae (the appendages that hold the fangs), plus the male has extended yet dainty rounded orange pulps (male sexual organs). There are over twenty Tetragnatha recorded for Australia and many require microscopic examination to separate them. They construct small orb webs that are set at an angle near or over water to catch insects that are attracted to the aquatic habitat, but during the day they tend to hug the stems of nearby round leaf sedges. I am not sure if they do this to escape the attention of daytime predators or to gain a cooler position amongst the sedges, or simply to wait for their small fly prey like midges and mosquitos that are more active from dusk to dawn.

The male is only slightly smaller than the female, but he still needs to lock her equally long fangs with his to safeguard himself. The female builds and attaches a fine white egg-sac to a sedge and may rest beside it during the day, although I have seen many left to their own fate, or maybe the female died or moved on.

The small orb web is very fine and unless viewed from the right angle is easily missed, and with the habit of the spider hiding behind the sedge, they are usually not noticed unless actively sought. The spiders are around 2 cm (3/4") in body length, plus with their long legs it makes them (overall) around 6 cm (2.5"), although very slender. Nevertheless, they are easily located when looked for, but being beautifully disguised in their habitat, you would never know they were there.