Building Bridges -- April 2008 and ODD SHOT MONDAY

If you are here for ODD SHOTS, please scroll down.


RuneE is sponsoring this monthly challenge on the first Monday of every month. Building Bridges is subject to open interpretation.

This "bridges between" meme has challenged me to think beyond the normal bridges we see on the water. I have some great ones of those since I live on the Washington side of the Columbia River. One day, I will also share them on this meme but today I decided I wanted to show a different kind of bridge. I like that this challenge is just once a month because then I have time to really think out my entry.


PLEASE CLICK ON PHOTO TO ENLARGE FOR DETAILS.
I ran across this photo I had taken last year of two spiders in side by side webs and my mind began to think of the bridges spiders make to trap their prey. The web construction itself is also a bridge for the spider to build the finished product.

I found this information in Wikipedia:

How spiders make webs
A orb weaver web anchored in a fork of a peach tree in winter
Spiders have several spinneret glands located at their abdomen which produce the silken thread. Each gland produces a thread for a special purpose. Seven different gland types have currently been identified, although each species of spider will possess only a few of these types, never all seven at once.
Normally a spider has three pairs of spinnerets, but there are spiders with just one pair or as many as four pairs of spinnerets, with each spinneret having its own function.

During the process of making a web the spider will use its own body for measurements, a very practical and ergonomic design feature of any web. This will allow the spider to move quickly and efficiently around its own web with very few faults. It will start with the most difficult part of construction, the first thread. The spider effectively utilizes the wind to carry its initial adhesive thread. With some luck the silk is released from its spinners and carried by the wind to a suitable adherable surface.

When it sticks to a surface the spider will carefully walk over the thread and strengthen it with a second thread. This process is repeated until the primary thread is strong enough to support the rest of the netting. After strengthening the first thread the spider will continue to make a Y shaped netting. The first three radials of the web are now constructed. More radials are added making sure that the distance between each radial is small enough to cross. This means that the number of radials in a web directly depends on the size of the spider plus the size of the web. After the radials are complete the spider will fortify the center of the web with about five circular threads. Then a spiral of non-sticky, evenly spaced, circular threads are made for the spider to easily move around its own web during construction. The spider then, beginning from the outside in, will methodically create the adhesive spiral threads. It will utilize the initial radiating lines as well as the non-sticky spirals as guide lines. The spaces between each spiral will be directly proportional to the distance from the tip of its back legs to its spinners.

This is one way the spider will use its own body as a measuring/spacing device. While the sticky spirals are formed the non-adhesive spirals are removed as there is no need for them anymore. After the spider has completed its web it will chew off the initial three center spiral threads then sit and wait. If the web is broken without any structural damage during the construction the spider does not make any initial attempts to rectify the problem. Indeed, there are many variations to constructing a web. This is just one possible way.

Webs allow a spider to catch prey without having to expend energy by running it down. Thus it is an efficient method of gathering food. However, constructing the web is in itself an energetically costly process due to the large amount of protein required, in the form of silk. In addition, after a time the silk will lose its stickiness and thus become inefficient at capturing prey. It is not uncommon for spiders to eat their own web daily to recoup some of the energy used in spinning. The silk proteins are thus "recycled."

The tensile strength of spider silk is greater than the same weight of steel and has much greater elasticity. Its microstructure is under investigation for potential applications in industry, including bullet-proof vests, and artificial tendons. Researchers have used genetically modified mammals to produce the proteins needed to make this material.


The spider, after spinning its web, will then wait on, or near, the web for a prey animal to become trapped. The spider can sense the impact and struggle of a prey animal by vibrations transmitted along the web lines.

Spiders do not usually adhere to their own webs. However, they are not immune to their own glue. Some of the strands of the web are sticky, and others are not. For example, if a spider has chosen to wait along the outer edges of its web, it may spin a non-sticky prey or signal line to the web hub to monitor web movement. Spiders have to be careful to only climb on the non-sticky strands of their webs.

A spider positioned in the middle of the web makes for a highly visible prey for birds and other predators, even without web decorations. Many day-hunting orb-web spinners reduce this risk by hiding at the edge of the web with one foot on a signal line from the hub, or by appearing to be inedible or unappetizing.



The symbol above is for a new meme that Katney started recently .

While most bus shelters have space for a wheel chair and a bench for at least two people and more room to stand under in case it is raining, on a walk, I recently spied this small bus stop seating near a church. To me it was definitely odd but am sure, welcoming to those who need to wait for a bus.