Saturday, June 02, 2007

Article: Spider safari

A wolf spider eating a grasshopper

Recently I got a new macro lens, opening the world of the teeny-tiny to my prying eye.

The lions and tigers of the macro world are, of course, the spiders. Every spider is a predator but they go about capturing their prey using a myriad of methods. All spiders have spinnerets, the organ on the back of their abdomen that lays down spider web, but they don’t all use it the same way.

Orb weaver spiders, like Charlotte in Charlotte’s Web, spin a new, complex, spiraling web each day. If you ever get a chance to watch that, do it. It takes a while but it is worth it. They never stop to rest. Makes me glad I’m not a spider.

Along with their web producing ability, all spiders are venomous. That doesn’t mean your average spider can harm a human. Here in Texas, about the only spiders people need to worry about are black widows and violin or brown recluse spiders. Neither of these makes a habit of biting people and generally bites are minor when they happen, but in rare cases they can be dangerous.

The venom of black widows is neurotoxic (acting on the nervous system) while that of violin spiders is hemolytic (causes damage to tissues). Spiders typically use their venom to subdue their prey, generally insects or other arthropods. Tarantulas are an exception, especially the large South American varieties. Some of these spiders can eat birds or small rodents. Oddly, tarantula bites, at least in the US, are not especially dangerous.

Keeping all this in mind, I set out one day to photograph spiders. I could have just looked around the house. We don’t use any pesticides or other poisons on our property which is good for us, good for the birds and rabbits but also good for insects and spiders. So there are a fair number of our eight-legged friends crawling the walls at my house.

That would have taken all the fun out of a spider safari though, so I headed to South Texas and Chaparral WMA, my favorite wildlife management area. I wanted to see some exotic arachnids in their unspoiled natural habitat. I was not disappointed.

Among the first spiders I saw was a large wolf spider. Like real wolves, these spiders are active hunters. They don’t loll about the web all day waiting for food to drop in, they go out, track it down and kill it. That’s just what this spider was doing. Clutched in its powerful jaws--called pedipalps and consisting of modified legs--squirmed a still-living grasshopper. Since spider venom typically starts the digestion process, there was no point to rescuing the hopper. Besides, I’m not sure I like grasshoppers better than spiders.

Next I spied a green lynx spider staked out on some small white flowers. I can hardly see these tiny spiders with my eyes but my camera lens blows them up so I can see the black, spiky hairs on each leg.

Moving on I encountered a large web with a little spider. The dense web formed a white tangle between branches in a bush. At first glance the strands seemed haphazard, completely lacking in the geometric beauty of an orb weaver’s web. However, the whole mess formed a neat funnel leading to a small spider, neatly hidden but ready to pounce.

The big excitement of my spider safari was the discovery of the elephant of the spider world--a tarantula. This one ran across the road at break-neck spider speed just as I was leaving. It didn’t care how many times I took its photo, it wanted out of there. It must have known about me. Even the tiny green lynx spider knew it was being watched. This one was just in a hurry and didn’t have time to deal with it.

The sun was heading down in the west when I pointed my Jeep back north with a successful spider safari safely cached in my camera’s digital memory.

For information on spider bites:
http://spiders.ucr.edu/dermatol.html
Good site for identifying spiders:
http://www.whatsthatbug.com/spiders5.html

Photo: A cabbage spider stalking prey on a sprig of white flowers.
Photo: Funnel spider waiting.
Photo: Tarantula crossing the road.

3 comments:

Gary Godfrey said...

Wow - I *really* like your new lens. Those are gorgeous!

Deanna said...

Spiders--ICK! But beautiful photos.

Coral said...

those pictures are great. And guess what, we have the same favorite wildlife management area! What are the chances?!