The world of spiders is one that intrigues many people. Arachnophobes may not want to know, but everyone else is probably curious about how many eyes spiders have.
Spiders have eight eyes – but this isn’t always the case. Some species of spiders have six or fewer eyes, and others have even none at all.
The common house spider, for example, has eight eyes arranged in two rows of four.
Reasons Why Spiders Have Numerous Eyes
So why the disparity? With their number of eyes, does this mean that spiders have better vision than we do? Not necessarily. This is a perfect example that more doesn’t necessarily equate to better.
The reason spiders have so many eyes is that they don’t rely on them as their primary source of vision. They use them more for sensing movement and detecting light changes.
This is why a spider can be facing the wrong way and still be able to see you coming – because it can sense the movement around it, even if its actual eyes can’t see you.
You may know it as the spider-sense, and it’s how they’re able to avoid becoming prey so effectively.
How do Spiders See?
Spiders actually have very poor vision, which is why they’re not able to see things in great detail. The multiple number of eyes helps them to make up for this by giving them a wider range of view.
While they may not have the best vision, spiders make up for it in other ways. They’re able to detect the slightest vibrations in their web, which helps them to know when prey is caught.
They also have an acute sense of touch, which is how they’re able to find their way around in the dark.
The sensitive hairs on their bodies can detect changes in air pressure and vibrations. All of these sensory abilities help spiders to be such effective predators, especially for their size.
With that being said, even those spider species that do not have eyes at all can still actively hunt for prey by using these other senses.
They can navigate their surroundings and detect their prey quite effectively, even without the use of eyes.
What Spiders Have Two Eyes?
Although very rare, there are a few spider species that only have two eyes. These are the ones belonging to the Caponiidae family, and they’re found in tropical regions.
They have two large eyes that are positioned centrally on their cephalothorax (the main body section of the spider). These eyes are larger than the other eight-eyed species of spiders, and they provide these spiders with excellent vision.
Aside from having only two eyes, Caponiidae spiders significantly vary from other spiders. They lack book lungs, which are found in most other spiders. They also don’t produce silk, and they don’t have venom glands.
There are over 119 spiders belonging to this family.
What Spiders Have Four Eyes?
Similar to those spiders with only a pair of eyes, spiders with only 2 sets of eyes are also considered to be a rare sight. Jumping spiders, which are part of the Salticidae family, are the only spiders known to have four eyes.
All other spider species have either six or eight eyes – but not these guys. They have two large eyes in the center and then two smaller eyes on each side.
The back pair of eyes are positioned further back on the cephalothorax, and they’re referred to as the posterior median eyes.
The large, central eyes are used for forward-facing vision, while the smaller lateral eyes provide them with peripheral vision. This gives these spiders excellent vision, which is how they’re able to jump such long distances and accurately land on their prey.
These spiders can be found in all types of habitats, including forests, grasslands, and even deserts.
What Spiders Have Six Eyes?
Considering that most spiders have eight eyes, it may come as a surprise to learn that there are also some spider species that have six eyes. You may know some of them as they’re quite common, such as recluses, spitting, and cellar spiders.
While not as rare as those with four or two eyes, spiders with six eyes are definitely in the minority. They have three sets of eyes that are arranged in a semi-circle on their cephalothorax.
The number of eyes can vary depending on the specific species, but they typically have two large eyes in the center and then four smaller eyes on each side.
Final Thoughts
The common average number of eyes for the majority of spiders is eight. These spiders with 4 sets of eyes may include but are not limited to those that are also referred to as net-casting spiders. They’re able to build webs that they can then use to capture prey.
Recently discovered in 2012, there’s another spider that doesn’t have eyes at all – the Sinopoda scurion. It is a huntsman spider and is commonly found in dark caves – thus, it does not require eyesight to help it with its nocturnal activities.
