Sunday, November 1, 2009
Sunday Spinelessness - crab spiders
Last month we heard about the worlds only known vegetarian spider - a remarkable discovery given the lengths to which the other 40 000 described species go to make animals into meals. There are the familiar web builders from the family Aranediae, active hunders like jumping spiders, the ambush hunting trapdoors and tarantulas and even the bolas spiders which produce a pheromone to attract moths so they can cast a sticky trap at them and, having caught them, draw them in like fish on a line. The subject of todays Sunday Spinelessness are the crab spiders, a family (Thomisidae) of ambush predators that use camouflage and a good deal of patience to get themselves fed.
The crab spiders get their name their name from those elongated front legs which are used to seize and hold on to their pray and from their tendency to scuttle about when disturbed. Most of the larger species, like the two above, hang out inside flowers waiting for would-be pollinators to get close enough for the spider to pounce. In fact, some crab spiders might even mimic the nectar guides of flowers to increase the rate that insects visit their flowers.
Some of the smaller crab spiders like the really tiny one above (probably from the consonant deficient genus Diaea) also hang out in flowers but others hide in the joins of bark, in the leaf litter or, like this one, in fronds of herbaceous plants. I'm not quite as patient as a crab spider so I don't have any photos of them in action but, as ever David Attenborough has a video on the topic: