Phidippus audax spider, with its principle eyes and two lateral eyes clearly visible. Image: Beth Jakob
One set of spider eyes helps the other - life science news

Biologists have figured out that spiders use their two forward-facing principle eyes can only track stimuli in their environment efficiently if they are helped by the six secondary eyes, the anteriolateral eyes. They came to this conclusion after completing experiments with a specially designed eyetracker, a tool normally used by psychiatrists to see where people are gazing while reading, driving, or watching moving objects on a screen. After gently and reversibly blinding the secondary eyes, it turned out that the principle eyes function like a torch light to see objects with great precision in a rather restricted area, so that the stimulus had to be right in front of the spider to track it. The secondary eyes direct the principle eyes to quickly locate and very accurately track disks moving at different speeds. This configuration of the visual system, in which one set of eyes depends on another set of eyes, is highly unusual and has not been observed in any animal before.

Read the full story: UMassAmhurst
Scientific publication: Current Biology