Explorit: Some spiders use vision, brain power to hunt prey

By Lisa Justice

You probably know that a spider has eight legs, but did you also know that many spiders also have eight of something else? That’s right, many spiders also have eight eyes.

But most eight-eyed spiders don’t have very good vision. They can see changes in light, motion and basic shapes. But they mostly rely on their extraordinary ability to sense vibrations to figure out what’s going on around them.

Yet the jumping spider, one of many spiders with eight eyes, has excellent vision. A jumping spider has a band of four eyes across the front of its head and an additional pair of eyes along each side of its head. The placement of its eyes allows a spider to look in almost all directions at once.

Such wonderful vision makes these spiders top-notch hunters. Jumping spiders have been observed learning new hunting techniques and using information that they observe to solve problems.

For example, some jumping spiders hunt their prey — other kinds of spiders — by sneaking up on them in their webs. They trick their prey into coming closer and closer until it can be caught.

But the jumping spider has to make sure that the trick works and the prey never figures it out. So the jumping spider will start out by observing its prey from a safe distance.

Where in the web does the prey hang out? How far away is the prey? What’s the safest route to the prey without being seen? The jumping spider will take all of these things into consideration before moving in to get its meal.

Sometimes a jumping spider will plan a specific route to get to its prey, sometimes leaving the web and going the long way around and losing sight of the prey to avoid being detected.

This sophisticated level of planning means that the spider has to make a map in its mind, taking into account where its prey is, which way its prey is facing, and the best way to sneak up on it. Then the spider has to remember this plan and the mental map for as long as it takes to catch the prey. That’s pretty good work for a brain the size of the head of a pin!

Jumping spiders use visual details to solve complex problems and so can you this weekend at Explorit’s “Forces of Nature” exhibit. Observe different noble gasses to determine what different stars are made of or test your cognitive skills at our problem solving table.

Saturday and Sunday will be the closing weekend for the “Forces of Nature” exhibit, so catch it before it’s gone. We’re making room to bring you some special spider events this summer.


* Sign up for Explorit Summer Camp 2012 online at www.explorit.org/camp. Camp begins June 11 and runs through Aug. 17

— Explorit Science Center is at 3141 Fifth St. and features a hands-on science exhibit open to the public the first full weekend of the month from October to June. For more information, call (530) 756-0191 or visit http://www.explorit.org, or “like” Explorit on Facebook at www.facebook.com/explorit.fb.

Special to The Enterprise

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