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Spiders

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Commander
6778.  Sat Apr 10, 2004 10:01 am Reply with quote

Spider silk is only about 1/200th of a millimetre in diameter and is so light that if a spider could spin a strand around the world it would weigh less than 6oz. Only one third of spider species spin webs; the rest either use silk traps or catch their prey directly.

All spiders are predators. They are also cannibals and will happily eat each other, often after mating. They can live for long periods without food so long as they have a constant supply of water.

A Daddy Longlegs is not a spider, although it is an arachnid. They have no narrow waist and the abdomen is segmented. They also have stink glands.

All spiders have fangs and carry venom, though few have fangs strong enough to penetrate human skin.

 
Jenny
6779.  Sat Apr 10, 2004 10:59 am Reply with quote

1. The first spiders on Earth lived about 300 million years ago, even before
the dinosaurs.

2. There are about 30,000 different kinds of spiders in the world and new
kinds are still being discovered.

3. Two female orb-web spiders (Araneus diadematus) went into space in a NASA experiment in 1973 and lived in a zero-gravity space environment. The spiders were able to spin perfect webs using a framework without the help of gravity.

4. Spiders have an important function in controlling insect pests that might otherwise destroy food crops and gardens. It is estimated that the weight of insects eaten by spiders in Britain each year is greater than the total weight of the population.

5. Eating mashed spiders was once thought to be a cure for the common cold.

6. Spiders are air-breathers and their lungs are called book-lungs because they are arranged in many layers like the leaves of a book. Water Spiders can spend up to 30 minutes underwater. Some Water Spiders build special sac-like webs underwater, with an opening at the bottom. Then they trap an air-bubble between their back legs and drag it underwater and put it inside the web-sac. They repeat this until the web is full of air, like a diving bell, and then they sit in there and catch passing water insects. Water spiders are also good at swimming, can catch small fish, and can run on the top of the water.

8. Spiders are arachnids. This class includes harvestmen, mites
and false-scorpions as well as spiders.

9. Spider silk is stronger than steel of the same thickness. It is also stronger than nylon and lycra. It is very elastic - dragline can stretch up to one third again of its length without breaking. Spider silk is used to make some parachutes, and it is being investigated for use in bullet-proof vests, because it is so strong and light.

10. Most spiders have 3 pairs of spinnerets, although a few have 4 pairs. Each spinneret can be connected to 5 or 6 silk glands, which produce different kinds of silk for different purposes. Spider silk is a protein, and spiders can eat it and recycle it.

Some of the different kinds of spider silk are:

- draglines (for safety lines and for the baselines or radius lines of a web)
- swathing band (for wrapping prey or for the outer layer of the egg sac)
- attachment discs which anchor the dragline, sticking it down
- sticky silk for snares
- light gossamer threads for ballooning - this can happen over very large distances. Spiders have been found in New Zealand having ballooned all the way from Australia.

11. Spiders don't stick to their own sticky silk as they have a special fluid which covers their legs to keep them from sticking. The fluid comes from a gland near their mouth parts.

12. "Mountaineer spiders": spiders pay out a dragline as they go, and anchor it every so often with a sticky attachment disc. If they fall, the dragline sticks to the most recent attachment disc and acts as a safety line.

13. Orb-webs are the commonest kind of spider's web, with lines radiating from the centre like the spokes of a wheel, and sticky threads connecting round and round like a spiral.

Other kinds of spiders web include:

- triangular webs
- ladder or space webs
- sheet webs - like a big horizontal sheet
- nets (some spiders cast a net of silk over their prey)
- cobwebs (although "cobweb" is a word we often use to describe an orb-web, a cobweb is really a three dimensional web like a cage or nest.)
- tangle webs
- tunnel or funnel webs.

14. Free-living (hunter, or vagrant) spiders don't make webs, or use only a single thread or small ladder of thread. Instead they sit and wait for their prey to come along and then grab it with their legs. Some of them are jumping spiders and can jump huge distances to catch their prey. Among the hunting spiders are wolf spiders, like the tarantula, which can live for up to 30 years.

http://www.powerup.com.au/~glen/spider9.htm
http://www.ufsia.ac.be/Arachnology/Pages/Kids.html

 
Jenny
6780.  Sat Apr 10, 2004 11:00 am Reply with quote

The spiders that starred in the movie Arachnophobia came from Avondale in Auckland, New Zealand. They are commonly called the Avondale spider. This spider originally came from Australia, and was first found in Avondale about 50 years ago. The Avondale Spider is a crab spider, and it is big, hairy and ugly, especially when magnified and and shown on the big screen.

 
raindancer
7500.  Sun Jun 06, 2004 6:47 am Reply with quote

I love spiders!

"The spiders were able to spin perfect webs using a framework without the help of gravity."

Now that's interesting.

 
Frances
7535.  Wed Jun 09, 2004 10:44 am Reply with quote

Is it true that house spiders can't survive if you put them outside in the garden? If so, I've murdered a lot of innicent wee beasties.

 
raindancer
7552.  Thu Jun 10, 2004 6:11 pm Reply with quote

"innicent wee beasties". Aye, poor wee things. Quick, away to the garden and gather them up!

 
Frederick The Monk
7556.  Fri Jun 11, 2004 2:43 pm Reply with quote

Don't give spiders drugs - it spoils their spinning. See http://www.cannabis.net/weblife.html for details.

 

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