Spitting Spider

Scytodes thoracica — and the other ~250 species of family Scytodidae — are the spitting spiders, one of the most behaviorally extraordinary arachnids in the world. The species' hunting strategy is unique among spiders: instead of weaving a snare web or actively pursuing prey, the spitting spider stalks within 1-2 cm of her target, then ejects a sticky-and-venomous silk-glue from her fangs at the prey. The discharge is fired in a rapid zigzag pattern (oscillating side-to-side at 1700 Hz, the chelicerae moving in a small arc) so that the silk lays down as a Z-shaped 'net' rather than a single thread, immobilizing the prey. The entire spit takes under 1/700th of a second (1.4 ms). The mechanism was first analyzed in detail by Suter & Stratton (Cornell, 2005). Once the prey is pinned, the spider walks over, delivers a venomous bite, and feeds. The chemical 'spit' is a mixture of silk proteins and venom synthesized in dramatically enlarged venom glands that occupy most of the cephalothorax — giving the spider's body a distinctive humped profile that is the basis for the family-level identification. Spitting spiders are slow-moving, cosmopolitan, and harmless to humans.