Spiders on Tiny Treadmills Give Scientists the Side-Eye

Thu, 15 Jul 2021 11:00:00 GMT
Scientific American - Science

Jumping spiders see more in their periphery than previously known

A smaller many-eyed mystery fascinates scientists today: members of the family Salticidae, or jumping spiders, with their front pair of large, round eyes and three smaller peepers on each side of their head. A new study explores how these arachnids see-and, more specifically, what they care about seeing.

The spiders "Are so relatable to us because they've got big eyes, and they look at you," says Nelson, an animal behavior researcher.

Unlike many arachnids, jumping spiders do not build webs or stay in one place.

Massimo de Agró, now a researcher at the University of Regensburg in Germany, suspected they did more: the spiders seemed to use their lateral eyes to pick and choose what they turned toward.

Studying a jumping spider's image processing is not as straightforward as implanting electrodes in its brain, as scientists might do with a larger animal.

To track where jumping spiders were looking, de Agró and his co-authors used a popular technique for studying bumblebees and other small invertebrates.

One of the images tested was a series of moving dots that represented the "Biological motion" of a spider walking from a side view-which the researchers were excited to find the arachnids could distinguish from randomly moving dots.

In addition to showing his spiders biological motion, he also created a dot display with a scrambled version of that same motion and another with random motion.

De Agró concluded that the spiders may turn toward a moving image when they want more information about it-implying that the anterior lateral eyes not only detect motion but also give a jumping spider enough data to classify the motion into categories of living and unknown.

De Agró adds that he hopes the study will help arachnophobes see these spiders in a new light, especially given the invertebrates' capability to engage in the kind of visual processing once presumed available only to humans and other mammals.