Why Do Spiders Have 8 Eyes?

Spiders are famously known for having eight legs (sorry for reminding you), but did you know what else they have eight of? Eyes! Why would one animal need this many eyes? Well, all of these extra eyes actually serve their own unique purpose…

The Better to See You With, My Dear

Many different species of spiders, especially jumping spiders, have four sets of eyes. They need these extra sets of eyes, as they do not easily catch their prey in webs — they hunt! These spiders will use their main eyes for basic vision (with sharp, colored vision that allows them to see ultraviolet light that humans cannot see). The other eyes assist in enhancing their ability to react to catching their prey and defending themselves against predators.

The Purpose of Having Secondary Eyes

With the main eyes being used for basic vision, the secondary sets of eyes are believed to be used to detect motion. This will aid them in response to a predator attack or the movement of their prey. The most important set of eyes on spiders are the Anterior Lateral Eyes (ALE). This set is the next pair of eyes after the principal eyes. They are forward facing, but are used mainly for this motion detection. Without this set of eyes, the spider would be in some serious trouble…

What Happens Without the Anterior Lateral Eyes?

When the ALE eyes are damaged (or covered during tests), spiders are usually unable to react to quick changes that would require them to defend or attack. Even with the principal eyes being as sharp as they are, the ALE eyes are completely in charge of detecting motion. To stress how important these eyes are — a spider with blocked out principle eyes would be far better off than a spider with blocked off ALE eyes.

Spiders have eight eyes for survival — they’re not just something to freak us out when we see them crawling through our homes. If you have a spider infestation (or any other infestation) taking over your home, give us a call and we’ll help you manage it!