Wonder Filled Webs
The following is compliments of the Happy Scientist.
This week’s experiment started as an idea for a Science Photo of the Day, asking why spider’s don’t get caught in their own webs. The more I thought about it, the more I thought that it had great potential for getting folks to actually go out and explore the wonders of a spider’s web.
To try this, you will need:
- a spider’s web
- a thin blade of grass or piece of string
A good time to find spider webs is in the early morning, before the spiders have dismantled them. Before a rain is also a good time, as the spiders know that insects are very active before it rains. This bit of weather lore is useful when you are hiking. If it is going to rain, invite a friend to lead the way, so you don’t get all those webs in your face.
Once you find a web, take a few minutes to look at it carefully. If the spider is there, be sure not to disturb it. If you are lucky, you will be able to watch as it moves around the web. Notice how it walks on the web, and that it never gets stuck. Why? If other creatures stick to the web, why don’t the spiders?
First, not all the strands are sticky. In a standard orb web, the strands that radiated out from the center are not sticky. They are a different kind of silk from the sticky strands that circle around the web. In fact, spiders can spin up to seven different kinds of silk for different purposes, ranging from thick, non-sticky strands for support, to tough, non-sticky strands for making egg sacks.
You can identify the sticky strands by carefully using a thin blade of grass to touch different strands. Be careful not to destroy the web, although if you wind up causing some damage, the spider can easily repair it. In fact, many spiders destroy their old webs (eating the silk to recycle it) and spin a new web every day.
Even if it walks on the sticky strands, the spider does not get stuck. Part of this is because it only touches the silk with the very ends of its legs, so there is not much surface area to get stuck. It is also thought that some species produce a chemical that keeps their feet from sticking to the adhesive of the silk strands.
There are over 38,000 species of spiders, with new ones being discovered every year. Recent discoveries include the world’s largest orb weaving spider and a species of spider that eats plants instead of insects. That means that there are thousands of different web designs. Try testing different webs, to see which parts are sticky. This can help you figure out how the spider uses its web.
A good example is the “cup and saucer spider,” which builds a saucer shaped sticky web that is horizontal. Above that, it builds many non-sticky strands that crisscross. Flying insects bump into the crisscrossed strands of the “cup” and fall into the sticky “saucer” below.
You can wind up your web wondering by eating a snack the way a spider does. Spiders don’t have jaws for biting and chewing. Instead, they have two sharp, hollow fangs. To eat an insect, they bite it with their fangs and inject a venom that kills the creature, and then digests its internal organs. After letting the prey digest for a bit, the spider sticks in its fangs and slurps out the liquified insect, just as you can slurp a milkshake through a straw.
Have a wonder-filled week.
***************************************
This weekly e-mail list is provided free of charge. You are welcome to print it in your newsletter, repost it on the Internet, etc., as long as you do not charge for access, and my name, and website link ( http://thehappyscientist.com ) are included.
