Spiders are a lot smarter than we give them credit for. Not only do they know how to quickly capture and contain prey for later eating, but researchers recently found that spiders also know how to weave their webs based on the kind of insect they want to eat.
An international team of scientists studying spiders ran experiments to test this theory and discovered that spiders customize their webs so that they capture the most nutritious and/or abundant meal in their environment.
We all know that spiders spin webs of a sticky thread-like substance that captures prey. The stickiness holds the prey in place, but the threads of the web act like a trampoline so that spiders feel a vibration when something's been caught. Eventually, that something gets eaten.
However, spiders don't always create the same kind of web. Often, they customize the web they weave based on what they've learned about capturing certain kind of prey. Usually this prey is crickets or flies, and this is what researchers focused on in their study.
When designing a web for capturing crickets, spiders must make their threads sturdy. Crickets use their legs for kicking and shaking the web, sometimes working their way out of the trap if the web is too weak.
"Crickets strike the web with more force and kick off against the web, causing pulse-like vibrations," says Dr. Sean Blamire, an evolutionary biologist at the University of New South Wales. "Flies buzz rather than pulse and put less stress on the web."
However, flies are just the opposite and get stuck easily and don't create as much movement. Spiders must design webs for them differently than they would for crickets so that they still feel the vibration of the flies' wings when they hit the sticky web.
Also, crickets contain more protein than flies, meaning they're more nutritious, but flies are usually more abundant. Researchers found that spiders generally decided how much more likely they were to trap one kind of prey over another and noted that their web weaving depended on that decision.
Spiders made this decision based on what types of prey occurred more often in their web. If they could get crickets more often, that's what they customized their webs for. However, if only flies seemed prevalent in their environment, they created their webs to capture flies. When deciding, a spider calculates the risks and decides on the best plan of action.
Photo: Andy Myers | Flickr