Wednesday, December 14, 2011

Brainy dust

I was sweeping the kitchen floor, when a speck of dust escaped from under my broom and ran for cover. Not fast enough; I was faster.

"Dusty", running still, under glass. She's about 1 to 1.5 mm long, not counting legs. It's hard to measure a critter that won't stop running.

Smithsonian Science posted an article yesterday, entitled "Brains of tiny spiders fill their body cavities and legs, Smithsonian researchers discover." They measured the brains of nine species of spiders, of all sizes, giant to pinhead size, like Dusty, here.
As the spiders get smaller, their brains get proportionally larger, filling up more and more of their body cavities. ... “The smaller the animal, the more it has to invest in its brain, which means even very tiny spiders are able to weave a web and perform other fairly complex behaviors,” said William Wcislo, staff scientist at the Smithsonian Tropical Research Institute. “We discovered that the central nervous systems of the smallest spiders fill up almost 80 percent of their total body cavity, including about 25 percent of their legs.”
I am amazed, but this does help to explain the ability of such a tiny bit of life to hunt, build webs, and escape dangers like my broom. I'm trying to imagine these legs, full of brains down to the knees. And brain surrounding the heart and lungs, the digestive system and muscles.

When she lost half a leg, did she lose IQ points?

Until I had time to photograph the spider, I kept her in a plastic container, 1 inch tall by 1 inch diameter. She spent her time building a messy web; when I opened the container, I found her hanging upside-down in the center, hoping to catch some lunch, no doubt.

I moved her, took photos, and released her to go back to work patrolling corners for dust mites and other invisible (to me) beasts.

A while later, I found a carpet beetle near the bedroom window, and dropped it into the same container without thinking. (I may not be as smart as a spider.) When I went to look at it, I found the poor beetle all tangled up in sticky web.

Carpet beetle, cleaned up. He's almost 3 mm. long.

Walking on the bottom of a leaf. Note the hooked claw.


  1. I really should visit more often! I learn the most amazing things here! Like the part about spider brains extending into their legs! I noticed the holes in the water in some photos I took earlier this summer. It is amazing what the camera can capture!!!

  2. I love that carpet beetle - I've never seen one before, but have heard of them.

    We have a garden spider that lives in my mom's office room above her computer. I don't know if she's still alive, she hasn't moved in a long time. We don't mind spiders in the house most of the time, when they don't bother us.

  3. That's funny, I just read through my comment and realized it sounded just plain WRONG. I meant that the SPIDER hasn't moved in a long time, not my mom.

    Mom is alive and well, and moves around a lot.

    Mom and I just had a wonderful laugh over this one!!! :=}


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