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Three days of eight legs
Last week was a week of spiders. Spiders in the classroom, spiders in the field, spiders in the lab! It was all part of our spider training programme, which Tom.bio is running in conjunction with the Shropshire Spider Group.
Field Identification of Spiders and Harvestmen - 7th October
Last Wednesday we kicked off with a course aimed at beginners, covering a general introduction to spiders and harvestmen, and the field techniques needed to have a closer look at them. Nigel Cane-Honeysett, vice-county spider recorder and leader of the Shropshire Spider Group, was as ever a font of knowledge on all things arachnid. Topics he covered included the basic taxonomy and anatomy of spiders, an introduction to the different spider families, some commonly encountered spider species, the different types of spdier web and what they can tell us, and some fascinating information about 'spider sense'.
As any budding arachnologist knows, the most important piece of equipment you can own is a spi-pot - and so Tom.bio's own spi-pot evangelist Rich Burkmar lead a Blue Peter-style session in which all attendees made their own spi-pots. You can see how it's done by watching our video guide.
After that we headed outside to test out our newly-crafted spi-pots, and to see what species we could find in and around the field centre. An early favourite - and one of the easiest harvestmen to identify, due to its characteristic way of holding its legs and its incredibly forked palps - was Dicranopalpus ramosus - a relatively new inhabitant of the UK, but spreading north as this NBN map shows. In addition to a spi-pot, no self-respecting spider hunter would venture out without a trusty electric toothbrush - not because we're unusually picky about dental hygiene, but because it's the best way of teasing out spiders such as Amaurobius sp. (lace-webs), Tegenaria sp. (house-spiders), and Segestria sp. (tube-web spiders) from their retreats. You can see this demonstrated in our video.
Spider Field Trip - Little and Great Orme - 8th October
The following day saw a minibus full of spider (and other invertebrate) enthusiasts head to Llandudno. Here we were met by spider expert and Llandudno local Richard Gallon, who lead us round the Little and Great Orme, two of the best spider sites in the country. The weather - and the spiders - were kind to us and we found some very exciting species, including Little Orme rarities Segestria bavarica and Great Orme specialities Drassyllus praeficus, Liocranum rupicola and Ozyptila scabricula.
However it was the purse-web spider Atypus affinis that many of us were the most excited about seeing. This species is the only UK representative of the Sub-Order Orthognatha, and as such is more closely related to tarantulas than to other British spiders. This species is very sparsely distributed in the UK - for example, known from only one site in Shropshire. Although we didn't see the spider itself, we did find many of its purse webs, which to an un-practiced eye can seem like plant roots or, worse, dog poo! This web structure is key to the way the spider hunts - it sits within the tube of its web, waiting for an unsuspecting insect to walk on the web - at which point, the spider bites upwards through the web and grabs the insect from below. Pity the poor fly - fangs emerging from the ground beneath your feet is truly the stuff of horror movies! Fortunately, like all British spiders, it poses no risk to people, reserving it's venom for flies and other insects...
We were also joined by Jenni Cox, who helps run the excellent British Spider Identification Facebook page - a great way of becoming familiar with spiders as there are always new photos being posted, and some of the country's most experienced 'spiderists' to offer identifications.
And the excitement didn't end with the spiders - Pete Boardman, who lead the FSC's Invertebrate Challenge project, also came on the trip and has written about some of the non-spider species we encountered on his blog.
Advanced microscope techniques for spider identification - 9th October
Our triple-header of spider courses was completed by an advanced spider course on the Friday, again lead by Richard Gallon. This workshop focussed more on the techniques needed to identify certain specimens, rather than the identification itself. Richard focussed on three separate techniques - physical dissection, reversible clearing with clove oil and permanent clearing with lactic acid. The latter two techniques allow you to see through the soft tissue, in order to view structures which would usually be buried or hidden. Clove oil is perhaps the easiest of these to use, as all it requires is the dissected part - or whole specimen - to be immersed in clove oil, which is pretty harmless stuff and certainly lent a festive smell to proceedings! Apparently it works by altering the refractive index of the specimen, allowing light to pass through the soft tissue. Using lactic acid to actually dissolve away the soft tissue requires a little more care, as the specimen must be heated in the lactic acid using a water bath.
However, I found the most difficult thing to master is the dissection itself, which is done under the microscope and requires immense hand-eye coordination! The spiders themselves are sometimes only a couple of mm in size; the epigyne, the part of the female reproductive system which is most commonly used in identification of female specimens, is much smaller still - sometimes hardly visible to the naked eye. Ordinary forceps are not up to the job - instead, Richard showed us how to sharpen them to a much finer chisel-shaped point point using a whetstone. Even with such a sharp tool, it's incredibly difficult to get right - my conclusion after one day of dissection was that I certainly wouldn't make a surgeon! But hopefully I'll improve with practice...
We were really pleased with the number of people attending all these events, and with the enthusiasm they showed for the subject. Hopefully some of Wednesday's attendees will join the Shropshire Spider Group and continue to build their knowledge. This trio of spider courses reflect Tom.bio's aim of offering courses to people at all stages up the 'pyramid of engagement' - from beginners to experts. Experts are often neglected when it comes to training courses, but most expert naturalists, including Nigel and Rich, Shropshire's 'spider men', would agree that there is always something new to learn! Many thanks to Richard Gallon for his expertise and enthusiasm.
Finally, some of you may know that last Thursday was National Poetry Day. In honour of this, I thought I should include a spider poem. Spiders are not typically used as romantic metaphors of love and devotion, but this poem, written in 1929 by E.B. White, is a lovely use of just such a comparison. And behaviourally correct (well, for some spider species at least!). Enjoy.
The spider, dropping down from twig
Unwinds a thread of her devising:
A thin, premeditated rig
To use in rising.
And all the journey down through space,
In cool descent, and loyal-hearted,
She builds a ladder to the place
From which she started.
Thus I, gone forth, as spiders do,
In spider’s web a truth discerning,
Attach one silken strand to you
For my returning.
For more information on Tom.bio's spider work, visit our Spider project page. For more information on invertebrate training courses run by FSC, see our upcoming FSC invertebrate courses. FSC also publishes a couple of ID resources for spiders: the Harvestmen fold-out chart, the House and Garden Spiders fold-out chart and the AIDGAP key to British spider families.