Spider identification

The number and location of a spider's eyes are a clue to its identity. CC image by Opoterser.

I've got a lot better at spider identification over the last couple of years. I'm not saying I can recognise many at a glance. But I feel like I've got some tools to make steps in the right direction.

A well kept field notebook will really come in handy with this group, because a dead spider floating in some ethanol definitely lacks some of the useful characteristics it had in life.

Make sure you note down what it was doing - running across the leaf litter? sitting in a web? crouching ominously in a corner of the house? Angling its little head at you and leaping off somewhere, like the jumping spider above?

And was it noticeably coloured or marked? After a while in some ethanol these clues do fade.

Was it posed in a characteristic way? (crab spiders and long-jawed orb weavers hold their legs in distinctive ways).

What habitat was it in?

All these are useful clues which you will forget if you don't write them down. And then you're making life a lot harder for yourself.

 Why not start off with a gentle introduction - you'll probably recognise these six common species from around your house, as showcased in the Natural History Museum's 'Spiders in your home' leaflet.

I've recently bought the new Wild Guide to Britain's Spiders which is full of lovely photos. It's not really got a key though, so although it's excellent for spider enthusiasm and finding out about your species, I'm not 100% convinced yet about how useful it is for a beginner to identify them right at the beginning. It certainly helps you appreciate the general demeanour and habits of the different families, which is great.

So I am still keen on LM Jones-Walters' "Keys to the families of British Spiders." We've got lots of copies. It's got two types of key - a dichotomous one and a lateral one. There's quite a bit of terminology but it's all very well illustrated so you should soon start to learn what features to look for. You'll need to look at your specimen under a dissecting microscope - please do arrange to come in and use one in OJ17. The arrangement and size of the eyes is really important. Once you've got a family, you can go back to the Wild Guide, or look at

the Collins Field Guide to Spiders of Britain and Northern Europe by MJ Roberts (of which we have lots of copies too). This has detailed illustrations which can get you to the right genus or species.You may have to look closely at the epigyne (reproductive opening) of a female spider, or the palps of the male (also involved in reproduction). It also has a wealth of colour plates to show the whole animals. These look slightly confusing to begin with because all the legs are interwoven to fit the creatures on the page! Also, the species all appear the same size, although they range in reality from 2 to 20 mm body length. That's where the Wild Guide is a definite improvement.

There are also some useful options online, but again you generally need a properly good look at your specimen under the microscope, to truly know if you've got the right creature:
The UK Spider and Harvestman Recording Scheme website has a full list of species and links to distribution maps and photos. If you check your suspect against this and find out it's only been seen in the north of Scotland, you might want to rethink your identification. (Admittedly spider atlases must be missing information, as only a limited number of enthusiasts are looking, but take it as a general guide).

There are also a limited number of photos on the British Arachnological Society's site - they don't seem indexed in a simple way, but at least if there's a photo of 'your' spider, you know that it's correctly identified (something you can't be so sure of in many places on the web).

Lots more links to reliable spider photos and id information here.

  Read on for how to preserve and present your specimens.