Friday, 2 October 2015

Dysderidae: Woodlouse hunters

My second spider family, Dysderidae, is a much smaller family in the UK, with only four species of wandering, nocturnal hunters. They are unusual in having just six, not eight eyes, arranged close together. They don't build a hunting web, but use their silk to spin cells under stones or logs where they hide during the day. Females wrap their eggs in silk and guard the egg sac. The most widespread is Dysdera crocata, a species that is actually cosmopolitan as a result introductions in North America and elsewhere, and that is often associated to human habitations.

It is a brightly colourful spider, with a flattened, elongated appearance. However, their most striking feature are their massive chelicerae projecting forward. These, together with their long fangs enables them to be able to hold the woodlice like pincers, and inject venom in the softer underside of the animal. Woodlice likely comprise the bulk of their diet.
I disturbed this D. crocata as it was feeding on a woodlouse under a pot.
 A mature female roaming in the open at night

A male and a female individuals in threatening position: fangs wide open, bodies and front legs lifted and keeping their distance from one another.

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