Spiders have fascinated and frightened humans for centuries. Their alien-looking bodies, intricate webs, and quick movements never fail to capture our imagination. But have you ever wondered how spiders perceive us? With their numerous eyes and unique visual systems, the world likely looks very different to a spider than it does to us mammals. In this article, we’ll explore how spiders see humans and other animals from their unique perspectives.
How Many Eyes Do Spiders Have?
Most spiders have eight eyes, some have six, and a few have just two. The eyes are arranged in patterns that vary between spider families. Jumping spiders, for example, have a rectangular pattern of four small front eyes and four larger rear eyes. Orb-weaving spiders have eight eyes arranged in two rows. No matter the arrangement, a spider’s numerous eyes allow it to have an excellent 360-degree view of the world, with the ability to see colors, shadows, movements, and details. Their eyes even allow them to judge distance.
|Spider Family||Number of Eyes||Eye Pattern|
|Jumping spiders||8||4 small front eyes, 4 larger rear eyes in rectangle|
|Wolf spiders||8||4 small front eyes in a row, 2 large middle eyes, 2 smaller rear eyes|
|Orb-weaving spiders||8||2 rows of 4 eyes|
|Net-casting spiders||8||2 rows of 4 eyes|
|Crab spiders||8||2 rows of 4 eyes|
|Lynx spiders||6||3 pairs of eyes in a hexagonal pattern|
|Recluse spiders||6||3 pairs of eyes in 2 rows|
|Tarantulas||8 (a few have 6)||2 rows of 4 eyes|
How Do Spider Eyes Work?
Spider eyes work very differently than human eyes. Each one contains light-sensitive cells instead of forming images on a retina. Rather than moving their eyes, spiders move their whole bodies to scan their environment. So each eye acts like an individual pixel, providing just a small part of the full picture. Information from all of the eyes is combined in the spider’s brain to create a full visual map. This is why spiders don’t get dizzy – their bodies stay still as they scan around with their eyes.
Some types of spider eyes are specialized for different purposes:
- The main eyes (called anterior-median eyes) have excellent vision and work together to identify objects.
- The secondary eyes (called anterior-lateral eyes) detect motion very well.
- The rear eyes (called posterior eyes) can detect light and dark but not much detail. They mainly monitor what’s happening behind the spider.
In web-building spiders, the middle pair of eyes has superior vision and can see color. Jumping spiders also have excellent vision in their large front eyes to identify and stalk prey.
How Far Can Spiders See?
Research shows that most spiders can see clearly between 20cm to around 2 meters away. Anything closer than 20cm appears blurry because their fixed-focus eyes cannot accommodate such near objects well. They rely on sensory input from leg hairs to detect very close stimuli. Distance vision varies between spider species. Jumping spiders have some of the best vision, with their front eyes capable of forming detailed images of objects 60-70cm away.
Can Spiders See Color?
Many spiders can detect some color, though they are not as skilled at color vision as humans. Their eyes contain two to three types of color detectors, compared to humans’ three cones types. This allows certain spiders to distinguish reds, greens, and blues to some extent. Jumping spiders and orb-weaving spiders have some of the best color vision among arachnids. The sensitive green receptors help them track plant-eating insect prey.
Can Spiders See Us Like We See Each Other?
Spiders do not see crisp, clear, colorful images like humans do. With their fixed-focus eyes and lack of overlapping visual fields, they see an impressionistic, somewhat pixilated version of the world. So no, they cannot see all the details of our faces, clothing, and expressions. But they can detect skin tone, hair or fur color, size and shape of bodies, and especially movement. Sudden movements, vibrations, and looming shadows likely signal danger or prey to a spider.
How Do Spiders Perceive Humans Visually?
To a spider, a human likely appears as a looming, fast-moving giant blob! Our facial features are indistinguishable but differences in skin tone and hair/clothing colors can be detected. Subtle movements of our hands and feet are very noticeable. Our voices, smells, and carbon dioxide output also alert spiders to our presence. Small spiders that rely on excellent vision, like jumping spiders, can see enough detail to identify a human as a potential predator rather than normal prey.
What Kinds of Cues Do Spiders Use to Sense Humans?
In addition to vision, spiders use the following senses to detect humans and other animals:
- Vibrations -spiders feel vibrations through their legs to sense footsteps and other movements
- Smell/taste – smells and chemical traces on the ground or in the air can signal humans or prey
- Touch – direct contact via webs or bristles alerts them to our presence
- Sound – some spiders may hear low-frequency sounds like voices
Jumping spiders likely get the most detailed visual information at a distance. But all spiders become more alert to humans approaching within about 2 meters, when our sounds, smells, and ground vibrations become much more apparent.
Do Spiders Recognize Owners?
There is no evidence that spiders can recognize individual humans. They do not have the visual acuity or mental capacity necessary for facial recognition. However, spiders can become habituated to the sights, sounds, vibrations, and routine care from an owner. So frequent gentle handling helps spiders see their owners as non-threats.
Can Spiders Tell Animals Apart by Species?
Research suggests spiders can distinguish different types of prey and predators based on sight, smell, and vibrations. Their vision is sharp enough to tell a bee from a fly, an ant from a beetle. And they likely recognize different animals like birds, lizards, rodents, and humans as potential threats. Exactly how spiders categorize animal species is not known, but their senses provide enough information to identify common prey, mates, rivals, and predators.
While spiders do not see the world or individual humans as clearly as we see each other, their specialized eyes and combined senses give them a detailed map of their surroundings. They perceive humans as looming, fast-moving giants compared to their small prey. Sudden movements, voices, and approaching footsteps signal our presence from meters away. So although you remain anonymously blurry in a spider’s eyes, your actions do not go unnoticed!