Tuesday, 30 March 2010

Woodlice hunting spiders

I occasionally come across Woodlice hunting spiders (Dysdera) in their silky day retreats when moving pots. These relatively large and brightly coloured spiders are strongly photophobic and run away from the light as fast as they can looking like they are dragging their bodies on the ground as they go. I haven't managed to take a decent photo of these spiders outside my plastic bug container (above) because of they dislike of lights. Dysdera spiders have traditionally been considered specialists on hunting woodlice. They have long, thin and highly mobile forward facing chelicerae (fangs) which it uses as pincers, catching the woodlice and then piercing the underside not as armoured side of woodlice. They are known to be able to deliver a painful bite if handled by brave humans. As they hunt during the night, when they come out of their retreats, their diet is difficult to study in the wild and there is some debate as to how specialised on woodlice these spiders are. In captivity, they are not fussy eaters, and feed on a variety of invertebrates, they seem to say no to nothing! What is certain is that they do eat woodlice, and the few times that they have been found in the wild with a captured woodlice suggests they might be an important part of their diet. Dysdera spiderlings raised on woodlice alone or combined with flies grew faster than those raised only on flies, sugesting some degree of physiological specialisation. In addition, not many spiders like woodlice - one of the few is the daddy long legs spider Pholcus- and here is a photo of it.
A Pholcus with its woodlouse prey in the kitchen

More information
S.D. Pollard, R.R. Jackson, A. van Olphen and M.W. Robertson (1995) Does Dysdera crocata (Araneae: Dysderidae) prefer woodlice as prey? Ethology, Ecolgy & Evolution 7:121-275. here.

J. A. L. Cooke (1965) A Contribution to the Biology of the British Spiders belonging to the Genus Dysdera. Oikos, Vol. 16:20-25. here.


Milan Rezac and Stano Pekar (2007) Evidence for woodlice-specialization in Dysdera spiders: behavioural versus developmental approaches. Physiological Entomology 32: 367-371. here.

3 comments:

Antje said...

That is amazing! :-D

Scotty Summerlin said...

Hey,

good info on these, but the reason I was looking for this is I took a photo of a spider in my garden last night and had never seen one like it before. It has the legs of a daddy long legs spider but its abdomen, for all the world, looks exactly like a woodlouse. I'd be more than happy to send the photo if you're interested, as I can't find anything online that looks like this thing.

Gui García-Saúco S. said...

I was looking for info about other naturalists going out at night and looking for inverts, and got here haha.

(Todos los caminos llevan a Roma jaja!)