Thursday 19 May 2016

What big eyes you have! Spider adaptation widened dietary net

A spider's unusually large and sensitive eyes help it catch bigger prey

Date: May 18, 2016
Source: University of Nebraska-Lincoln

Evolving the largest eyes among all known arachnids may have helped the net-casting spider add walking prey to its airborne menu of midnight snacks, says new research from University of Nebraska-Lincoln biologists.

Doctoral student Jay Stafstrom reached the conclusion after two months living out of a tent in a Florida state park, where he observed how the nocturnal species Deinopis spinosa hunted with and without the aid of secondary eyes roughly 2,000 times more light-sensitive than human eyes.

The net-casting spider earns its name by spinning a rectangular band of woolly silk to capture prey while rappelling upside-down from a single thread. When the time comes, the spider lunges forth and stretches the net to engulf prey in one fell swoop that lasts about one-thousandth of a second.

Stafstrom discovered that the spider snared prey about 3 1/2 times more often when relying on its massive secondary eyes than when those eyes were covered by vision-impairing dental silicone. But the effect seemed to depend on whether that prey traveled by leg or by wing.

While the silicone had no discernible effect on the species' ability to snag flying prey, it greatly reduced the odds of the spider capturing a crawling critter. Though one of every four specimens without the silicone blindfold would capture prey that walked their way -- roughly the same proportion that caught prey flying through their attack radius -- none managed to snare a walking meal while their vision was impaired.

No comments:

Post a Comment

You only need to enter your comment once! Comments will appear once they have been moderated. This is so as to stop the would-be comedian who has been spamming the comments here with inane and often offensive remarks. You know who you are!

Related Posts with Thumbnails