Tuesday, March 13, 2012

Can we say a spider is courageous?

I'm back! Now, about that spider ...

Laurie brought me a small, fat spider a couple of months ago. As far as I can tell, it is a male false black widow, Steatoda grossa. (I could be wrong; I often am.) I was getting ready to clean out old duff and add a few tasty morsels to his cage the other day, when I noticed that he was hanging oddly in a mess of catkin fluff.

Seen from the belly, against the light.

Usually these spiders sit in an elegant pose, with the legs arched high above the body, "toes" spread wide. Now he (answers* to "Spotty") was hanging belly-up, with each pair of legs meeting at the tip. I thought he might be sick, or unhappy with the catkin fluff, which bothers some spiders, so I touched him with the tip of my tiny paintbrush. He didn't move. I gently pulled the catkins fluff away, leaving him hanging by his own web. He promptly let go and dropped to the bottom. So he was alive and responding. I let him rest. The housecleaning could wait until he was ready.

Half an hour later, I checked back. Spotty was lying upside-down on the bottom of his box, twitching feebly. I looked closer; what was wrong?

Nothing wrong, at all. He's molting. 7:14 PM.

He seemed to be still connected to the old skin, by the tips of his legs; it moved when he twitched. He looked exhausted, pale and wan; his cephalothorax and legs were almost transparent.

I notice, looking and measuring the photos, that his new legs are about 1/3 longer than the old ones.

6 minutes later, 7:20

I watched for the next 35 minutes, as he struggled, weakly - oh, so painfully weakly! - to disengage from the old exoskeleton and to turn himself upright. At times, it looked as if he were about to give up and just let himself die; it was hard to let him suffer and not try to help.

Over half an hour later. 7:57 PM.

He finally righted himself and struggled over to a pile of duff. There he rested for a long time. He didn't have the use of the legs on the left yet; they lay together, stretched out; at least the joints were working on the right.

An hour later, as I watched, he dragged himself upright, and climbed an inch up the duff. Another rest. Next time I looked, he was hidden.

By the next evening, he was up and about, hunting, looking like his old self. But a bit bigger.

The legs are still tranbslucent; by the next day, they'd darkened and developed their old sheen.

BugGuide has a series of photos of another small spider molting; comparing with mine, I realized better what was happening to Spotty, here.

In the first BG photo, the lynx spider is hanging in the same position; upside-down, toes together.
Typical position assumed by most spiders before shedding.
Good! Now I know, for next time.

Here, the legs are half in, half out of the old skin. 
Stretching. This is performed by most spiders as soon as they are free of the old skin.
This is the first time I've seen a spider molt. The whole process, from start to finish, where he could actually walk away, took about 2 hours. It looks extremely stressful, sort of like childbirthing in reverse. And to think they go through this every few months!


  1. A number of years ago, an Araneus Diadidimus found its way into my bedroom. one night, I found it walking across a thread boldly, then hanging in one spot for a while. I suspected she was just relocating her snare, but like you, realized she was going to molt. it probably took an hour. i'll post the pics when I get the chance.

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