Spider headaches

from Wikimedia Commons

 Yesterday, enthusiastic and determined student A came to examine her spider specimens under the microscope. I was feeling alright about being able to help, having done a little bit before, and having taken useful things in on a day course with people who actually knew what they were doing.

But it didn't really work out as planned. And that was because I insisted on throwing us into the dichotomous key. And then we just ended up drowning in the not-exactly-beginner-friendly language. I'm not saying the key is rubbish, that would be unfair. But it's not an encouraging way for the beginner because you have to wade through a lot that would seem obvious to the expert, but is very draining (and largely irrelevant) to the beginner. Astoundingly, student A kept awake and motivated. I however was desperate for a cup of tea and wanted to dash the petri dish across the room.

I just wanted to show that matching a specimen with photos on the internet is not good enough for spiders. Yet I didn't want to inflict such pain and confusion on a first time arachnologist. But there is a middle way. What we should have done (I think) was to draw / note down basic features of the spider, such as:

- The arrangement and number of its eyes (spiders have 6 or 8 in various sizes and configurations)

a spider sketch from my notebook

- The size of its body (in millimetres. You can borrow some vernier callipers from me, it might be easier than a ruler. Spider lengths are measured fom the front of the cephalothorax to the hind end of the abdomen - essentially, from its face to its bum. Not across their legs, although that can make for a scarier sounding distance).

A lovely banana spider from Florida (CC David Maiolo) and its length.

- Whether it had a web or not (and what form it takes if it does)

- Any unusual shape to the body or particular markings / colouration.

- Any differences in the length of the different pairs of legs, and the general air of stoutness / spindliness with regard to body vs leg size.

These are all simple things, and to be honest this must be how an expert will approach a new spider in their head. They're looking at the overall picture to begin with, not immediately delving down into the finer details. To be fair the key does do this a bit, because (to quote my tutor) it "gets rid of the bananas in the fruit bowl." That is to say, the key tries to get all the weird and obviously different species out the way first. But this feels like a struggle to the first-time user of the key, because they don't realise that this is what's happening. This is partly to do with a lack of illustrations, I think.

The rare Ladybird spider (Ereus Sandaliatus). CC Viridiflavus. A "banana in the fruitbowl."

Armed with the information in your notebook, you can narrow down a few possible families using the lateral key later on in Jones-Walters book. That shows you much more clearly what the differences in body shape, eyes, webs and so on are between the different families. It's not going to solve everything, but I think it's a good start. You can worry about the dichotomous family key when you've got confidence from the lateral one, and go on to look at them in detail in Collins, for example. There are lots of things you'll probably have to / want to get to grips with, like spinnerets and calamistrums and trichobothia and epigynes. But give yourself a break to start with.

Anyway. Spiders. So many people seem to want to do them this year (but curiously no-one last year). This is to warn you - they're not going to be particularly easy. But they are interesting and if you can invest a bit of time and effort I think it will pay off.

Spider encouragment update.
Student S came in this week, and she was able to identify several of her spiders in a few hours' determined studying. This was good. We did use the approach above, and once a likely family had been narrowed down, we turned to Collins. Then it was a matter of choosing between the species in that family - some are rare and some are not British, which is helpful, but then you can be left with several likely candidates. Luckily, Collins has excellent illustrations of the reproductive bits of male and female spiders, and the distinctive shape of these make you feel quite confident about picking one species over another. That's where the lovely microscopes make zooming in so easy (even if getting an angle without a leg in the way can be difficult).