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Monday, 2 November 2015

Standing up for spiders

October 31

Halloween, and the slightly saddening, but probably inevitable, reinforcing of fears and prejudices about creepy crawlies.

If an arachnophobe, best scroll away now. This morning there appeared a fantastic sheet web, seemingly the product of one night's work, stretched like a diaphanous trampoline between a spider plant, appropriately enough, and an indoor fern. In the middle, upside down, was a spider; except not a spider: on closer examination a left behind exuvium, after a moult.

 Any other species sharing my flat gets identified - that's the deal. So, off to the microscope.

These days I find spiders just too fascinating to be scary. The discarded exoskeleton was perfectly detailed, with markings, spines, even the trichobothria, vibration-sensing outward protruding hairs, visible in a single row along the lower legs. The carapace was neatly split in two, flipped up like the lid of a snuff box, allowing the spider to emerge in its new and larger suit of armour.

The absence of 'boxing glove' palps meant this was a female. The old skin also preserved the sculpture of the eight eyes, and the jointed outer spinnerets, which made it possible to identify to Family Agalenidae, that is, the tube web spiders, which includes Tegeneria, the house spider. Although we think of 'the house spider', this is a group of 5 or so closely related species, including Tegeneria domestica and the less homely sounding Tegenaria gigantea.

This was as far as I could get, but a suitable addition to the guest list. Of other spiders which have made the trip to the microscope, Steatoda grossa is common - one sometimes lives behind my kettle plug - and once S. bipunctata, and the velvety-looking Gnaphosid mouse spider Scotophaeus blackwalli. Most beautiful, and what has become my favourite, was the 'X', or 'window sill' spider, Zygiella x-notata, with its silver-chased abdomen.

More info at

Zygiella x-notata

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