Ways of Webs
Today's heavy morning dew provided me with the opportunity to photo capture a variety of spider webs. Running around, soaking my shoes and trousers, with camera and tripod in hand, I had a great time of it. What amazes, always, is the plethora of options and strategies our natural world serves up.
The evolution of spider silk is well covered in this book, mentioned in a recent blog post:
http://www.lesliebrunetta.com/works.htm.
So, let's begin our walk. The first, and possibly the most abundant type of web seen today, below:
This creation is known as a 'bowl and doily' web, perhaps reminiscent of Victorian era finger bowls placed upon a doily. When one thinks of the spider's need to both eat and avoid being eaten, this is one sweet design. Prey are caught within the bowl, while the spider hides on the sheet beneath, offering protection from below. When a meal presents itself, the spider cuts through the bowl's bottom and has at it. Note, above the bowl, strands are attached to surrounding foliage, thus creating directional trip lines. Here is another picture of a similar web:
There are many types of ground webs, often seen in our yards and along woodland paths. Funnel-weavers, or grass spiders, (of which there are over 1000 known species), utilize a similar strategy by stringing up trip lines above their trap in order to further increase their catch.
Spiders spin task-specific silk of different chemical compositions, some sticky, some not. The following picture is of a funnel web. Keep in mind that the silk sheet surrounding the funnel is not sticky...for what should be obvious reasons.
Here is another example, see the entrance upper middle of picture:
Finally, the vertical orb web, with which most of us are quite familiar, is often the one we find tangled in our face and hair before seeing it. This is not the most 'advanced' web, according to Leslie Brunetta, but it survives because it works. The common garden spider, an Argiope species, is also well known to us because of its striking colors and size.
It is argued that the 'decoration', seen to the right of our spider, could serve any or a sum of the following purposes:
-warning to larger animals, such as birds, thus conserving the efforts made in web construction
-attractant for insects (the thick aciniform silk ribbons that make up the broken X formation, unlike the other silk threads in the web, absorb ultraviolet light, thus stand out)
-structural stability
-
The evolution of spider silk is well covered in this book, mentioned in a recent blog post:
http://www.lesliebrunetta.com/works.htm.
So, let's begin our walk. The first, and possibly the most abundant type of web seen today, below:
Spiders spin task-specific silk of different chemical compositions, some sticky, some not. The following picture is of a funnel web. Keep in mind that the silk sheet surrounding the funnel is not sticky...for what should be obvious reasons.
Here is another example, see the entrance upper middle of picture:
It is argued that the 'decoration', seen to the right of our spider, could serve any or a sum of the following purposes:
-warning to larger animals, such as birds, thus conserving the efforts made in web construction
-attractant for insects (the thick aciniform silk ribbons that make up the broken X formation, unlike the other silk threads in the web, absorb ultraviolet light, thus stand out)
-structural stability
-