opalescent-potato  asked:

You seem like the right person to ask this question: do spiders have to practice spinning webs to get good at it? Do young spiders fuck up their webs sometimes?

This is a really interesting question, and it took a bit of digging to find the right answer, which is… sort of yes and sort of no?

The ‘no’ part comes from the fact that spiders are born knowing how to spin webs- there’s no stepwise process of learning. They actually have, encoded within their genes, very specific algorithms to use when constructing webs.

Below are two figures from a paper that successfully imitated the process of building a spider web using a computer program by splitting the process into a few very simple rules:

So despite how complex the process seems to our eyes (and it would take a human some practice to get it right) evolution has split the process up into easily-encoded chunks for the spider brain to have ready from the get-go.

(This all applies to ORB webs, though. I didn’t find much information on how the construction of funnel webs, tangle webs, etc. are encoded- one would assume it’s similar, though.)

However, I DID say that the answer to your question is both yes and no. Despite the fact that the process of making a web is essentially hardwired into a spider from birth, there is still a surprising degree of plasticity (i.e., flexibility) to the behavior.

There is a lot of value to this for web-spinners because many species will build new webs every day. Studies have found that the spider’s personal experiences will modulate how they construct certain details within their webs.

For example, one study found that spiders which had recently eaten used less capture silk (that’s the sticky stuff) when they made their next web, probably because they didn’t feel like expending the extra energy when they were already full. (You and me both, spiders.)

In another study, researchers compared the number of webs a spider had spun over its lifetime with their top-bottom asymmetry. Let me explain that real quick before we go further: spiders tend to have better prey capture success when their webs have larger bottom halves than top halves. This is because orb webs are oriented vertically, meaning that a spider sitting in the very center of the web is going to reach the bottom faster than the top because of- well- gravity. Faster prey grabbing means prey are less likely to escape while the spider is scrambling over to it.

Here’s an asymmetrical web with a larger bottom half (left) compared to a more symmetrical one (right).

The researchers found two things: first, the more experienced a spider was overall, the bigger the bottom half of her web was compared to the top. However, when researchers placed more prey into the top half of the web than the bottom half, the spiders responded by making more symmetrical webs, i.e., putting resources back into the top half that they would have used in the bottom half.

Taken together, these two observations suggest that experience and learning do play a role in how a spider constructs her web, even if the main gist of it is encoded from the beginning. And that’s pretty neat!

Refs-

Heiling, A. M., & Herberstein, M. E. (1999). The role of experience in web-building spiders (Araneidae). Animal Cognition, 2(3), 171-177.

Herberstein, M. E., & Heiling, A. M. (1999). Asymmetry in spider orb webs: a result of physical constraints?. Animal behaviour, 58(6), 1241-1246.

Krink, T., & Vollrath, F. (1997). Analysing spider web-building behaviour with rule-based simulations and genetic algorithms. Journal of theoretical Biology, 185(3), 321-331.

Venner, S., Pasquet, A., & Leborgne, R. (2000). Web-building behaviour in the orb-weaving spider Zygiella x-notata: influence of experience. Animal Behaviour, 59(3), 603-611.