Tuesday, 11 February 2014

What's lurking in the Oxfordshire undergrowth?

The prey shifts nervously, raising its head from grazing under the hunter's multifaceted gaze.  Sensing oncoming eight-legged movement, the would-be prey item strikes out with its forked tail, catapulting itself backwards and spinning head-over-heels through the sky as the pincers of the wannabe-predator close on empty air.  This is the seriously weird world of the British microfauna, and it's at least the equal of the charismatic macrofauna you can see on TV.

Pseudoscorpions - the thwarted predator from the scene above - are symptomatic of how this miniature jungle is overlooked.  They look amazingly similar to 'real' scorpions, complete with huge pincers, but lack a sting at the back end.  Although they look far too exotic to be British, in fact we've got at least 27 species and many are quite widespread, particularly in moss, leaf litter, and under bark.  I found this one - Chernes cimicoides - under the bark of a dead Eucalyptus around the corner from my house last weekend.
Chernes cimicoides
Having wandered down to the river Thames to see how high the floods were getting (answer: worryingly high), I spotted that the dead tree had some loose bark and had a bit of a poke around underneath.  These kind of sheltered spots are some of the best places to find insects over the winter, and there were plenty here - woodlice (Porcellio scaber and Androniscus dentiger) scuttled in all directions when exposed to the light, while bean weevils (Bruchus rufimanus) tried the opposite tack and froze, pretending to be lumps of misshapen wood.  Ladybirds (Harlequin Harmonia axyridis and 2-spot Adalia bipunctata) trusted in their defensive chemicals and warning colouration to repel me, sitting in obvious groups, and it was when peering at these (I'm very fond of ladybirds after studying them for four years for my PhD!) that I noticed a 3mm flattened, rounded blob tucked in nearby.  Spotting the pincers I almost jumped for joy - my second ever pseudoscorpion!
Chernes cimicoides in its overwintering cell underneath bark
Reaching 3mm long in Britain and only up to 12mm in the largest species yet found worldwide, these tiny arachnids are close cousins of spiders, harvestmen, scorpions, mites and ticks in Britain, and of whip-scorpions, vinegarroons and camel spiders overseas.  They may not be cute and fluffy but they are amazing to look at, and in their habits - the first I ever saw was in a photo that a friend had sent me to identify a beetle.  When you looked closely, an odd bulge on the antennae was clearly a pseudoscorpion, clinging on for grim death as the beetle unwittingly flew it to pastures new.  And when was the last time you saw a lion do that?
A pseudoscorpion on the antennae of a Black-headed Cardinal beetle (pic courtesy of Jo Cartmell)

5 comments:

  1. Great post - I really like pseudoscorpions but have never managed to get any funding to work on them

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  2. Thanks- they're great little things, sadly understudied

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  3. Uropygids: http://en.wikipedia.org/wiki/Thelyphonida :)

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  4. Thank you so much for sharing this with us, it helps me a lot, really appreciated!

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