Friday, July 28, 2017

Scytodes thoracica - Spider - BIODIVERSITY

Scytodes thoracica is a spitting spider, so-called because it spits a venomous sticky silken substance over its prey. Its size ranges between 3–6 mm. It has six eyes instead of the eight spiders usually have. Scytodes thoracica is nocturnal. It prefers warm temperatures and is not rare inside houses. In Southern Europe, it can be found under stones outside houses. In Northern Europe it can only be found in houses. They can be found worldwide.

This species has long, thin, legs, and are glabrous (hairless), with the exception of short sensory setae scattered over the body. These spiders are also easily identified by their oversized cephalothorax (prosoma), which slopes upward towards their posterior ends. Their abdomens (which are roughly the same circular shape as the cephalothorax) slope downwards and are only slightly smaller than the cephalothorax. Like all spiders, these two body tagmata (segments) are separated by a thin pedicel (waist-like connector).

Large, well-developed poison glands are located in the cephalothorax. These glands are divided into two parts: a smaller, anterior compartment which stores venom and a larger, posterior compartment which contains a mucilaginous substance. These spiders produce a gummy substance which is a mix of the two substances and is excreted by their fused chelicerae, which can not be moved separately. Scytodes are ecribellate, lacking the silk-spinning organ (cribellum) of some other spiders. They have a single tracheal spiracle.


Photo credit: André Karwath

Source: Corina Marinescu

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