| Information sur la photo |
Copyright: Rimantas Kisielius (rimas)
![Gold Star Critiquer/Gold Note Writer [C: 155 W: 3 N: 610]](http://i1.treknature.com/misc/g-n-g.gif) (4273) |
| Genre: Animals |
| Média: Couleur |
| Date de prise de vue: 2005-08-22 |
| Catégories: Insects |
| Appareil photographique: Canon EOS 300 D, Canon EF 28-105 |
| Exposition: f/8, 1/250 secondes |
| Versions: version originale |
| Date de soumission: 2006-03-12 7:36 |
| Vue: 762 |
| Points: 2 |
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| [Ligne directrice - Note] Note du photographe |
Scientists had shown that the web building skills of spiders is in-born, i.e., they do not learn from their parents. Scientists isolated a new born baby spider in a test tube and keep it away from other spiders. They feed them until the spider became an adult. Then they released it from the test tube. The spider started to build the webs, with some more practice on their own, it build webs as good as normal spider.
But then as the whole spider weaver group, how did they acquire the web building technique? This is a long evolution story. In short, with some guessing, the story are told as follow. Hundreds of millions years ago, the spiders did not build webs. No insects could fly. The spiders were just walking and jumping on the ground chasing for the insects. They did use silk but just to make egg-sacs to protect the egg they laid. One day, a spider was born with the behaviour that it would attach the silk to the floor when they walked or jumped. This behaviour had some advantages. It was easier for the spider to go back where it was by follow the silk they laid to return. More important was when it jump to catch the prey, if it missed, it could climb and return back where it was by holding the silk. If not the silk, it would be a long way to go back. Because this was a good behaviour, this characteristic was inherited by its off-springs. Then a group of spiders walking with a silk attached behind became a new species.
After a few million years, more and more different kinds of insects were flying in the sky, and very hard to catch. One of the spiders in this group evolved another useful behaviour. When it jumped backwards and forwards, chasing the flying prey between branches, with the silk attached from its back, it accidentally built a very messy web, or we could not even call it a web. However, this messy thing did entangle some prey sometimes. So the spider, besides chasing the prey, it could also go back to its messy web to look for some prey. Of course this behaviour was also passed to its off-spring.
www.geocities.com/brisbane_weavers/Garden_sp.htm |
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