The Atavism

Sunday, March 21, 2010

Sunday Spinlessness - Waste Not

Just a quick one today. A few weeks a go I used a picture of a male Cambridgea spider to spring off into a half-baked conversation on arachnophobia. That male had probably wandered into the warmth of our house after paying a visit to a female who has a web attached to the downpipe by our kitchen window:

cambridgea web

During the day the web's owner hides in a retreat (in this case right behind the joint in the downpipe) but at night you can see a very impressive spider sitting under her web, waiting for some tasty morsel to get trapped. Cambridgea are really forests spiders, if you hunt around a decent piece of native forest and you are bound to find a similarly constructed, but much larger, web. In the forest expectant Cambridgea mothers obscure their egg cases with twigs and dried leaves. Apparently our kitchen wall did offer much camouflage when our Cambridgea mother

cammegg2

You really should click on that image and see the high-res version, it's pretty cool. In order to grow, spiders have to cast off their rigid exoskeleton. You can see here our Cambridgea mother has used her discarded exoskeleton to help obscure her egg case!

The exoskeleton also gives you a clue as to how the spider has achieved its moult - the cephalothorax (the part of an arachnid body that includes the head and the thorax) is popped off and the spider pulls itself, legs and all, out through that gap. The last step of the process is photographed here.

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Posted by David Winter 10:56 AM

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