Spiders have brains, but not in the same sense that people do. A spider’s organs are located in its cephalothorax, where its head and thorax join. The brain isn’t a squishy, pink glob like ours, but rather, smaller than a pinhead, extending nerves throughout the spider’s body.
Research has shown that despite their size, spiders are remarkably clever creatures, and some are capable of forming strong social bonds. While their intelligence won’t score high on an IQ test, they’re well-suited for their environments.
Spiders Brains Allow for Basic Function
Because spiders themselves aren’t very large, neither are their brains. Some scientists can’t see spiders’ brains up close without using specialized tools. Regardless, spiders’ brains allow them to have the same senses that mammals do, including:
- Sight. Despite having six to eight eyes, spiders can’t see very well. According to the Australian Museum, spiders rely on their other senses for hunting and defense. They can only see polarized lights—limiting what they can view.
- Touch. Spiders have specialized bristles and hairs all over their body that send messages to the brain. This allows them to capture prey, defend themselves, and even communicate with fellow spiders.
- Smell. Spiders rely on pheromones to communicate with one another. While they don’t have noses, spiders pick up odors using their pedipalps. These are special sensory organs that let a spider navigate the world around it.
- Taste. A spider would be a bad food critic; they can’t taste in the same sense that we do. Instead, they rely on their pedipalps to determine whether something is consumable.
- Audio. Just like with their sense of taste, spiders don’t hear the same way we do. They instead sense vibrations, activating their fight or flight response.
Spiders Only Partially Rely on Their Brains
In the previous section, you may have noticed the word pedipalps. What are those, anyway? These are important sensory organs that help a spider eat and survive. A spider’s pedipalps are near the spider’s mandibles, and they look like a smaller set of appendages. It’s basically like having a smaller set of hands.
Arguably, spiders rely more on their pedipalps than on their brains. What’s more, they’re not the only animal in the world that’s come to evolve with this toolset. Other animals that rely on their pedipalps include:
- Horseshoe crabs. These arthropods use their pedipalps to find food on the ocean floor.
- Scorpions and spiders. These are used for holding or capturing prey.
- Sea spiders. Some species of these underwater critters use pedipalps for feeding and cleaning themselves.
Some Spider Brains Allow for Socialization
Unlike ants and bees, spiders aren’t known to live in vast colonies. Often, they live alone, only coming into contact with another insect to eat it. However, research from Australian National University notes that some spiders have evolved to become more social. This indicates that some species of spider may have more developed neural systems (brains and nerves) than others.
One social spider is the huntsman spider. They are large, long-legged arachnids that sometimes feed on birds and other small mammals. These spiders are starting to evolve to gather in groups, usually for eating and mild socializing. This means that their brains are capable of memory and positive associations.
Meet These Smart Spiders
Some spiders that display enhanced cognitive processing skills include:
- Fringed jumping spiders. Not exceeding 10mm, a fringed jumping spider develops a cunning way of capturing its prey. Per the Australian Museum, it uses a trial-and-error system to determine what works and what doesn’t––nearly unheard of in the bug world.
- Kleptoparasitic spiders. This refers to a group of spiders that have evolved past the ability to spin webs. Instead, they steal the prey ensnared in other spiders’ webs. This demonstrates an advanced ability to plan ahead and avoid detection.
- Trapdoor spiders. Trapdoor spiders create elaborate traps that ensnare unsuspecting prey. This level of intelligence requires them to have planning, forethought, and an understanding of what works.
National Geographic notes that, for some species of spider, the smaller the insect, the bigger its brain. What this means for spiders’ intelligence and reasoning is still unfolding.
Could Spider Brains Evolve?
One of the great things about nature is that it’s always evolving, whether for better or for worse. Even though one person might not see a spider species evolve in their lifetime, changes over hundreds of years could produce a deeply intelligent spider.
For this to take place:
- Spiders with large brains must reproduce. Evolution is a game of genetics. Spiders with similar traits must reproduce to propagate and evolve a bigger-brained species.
- Spiders would have to be larger. In many cases, smarter animals have larger brains in relationship to their body. So, to accommodate more brain mass, an intelligent spider would be quite sizeable.
- Spiders would have to find their niche. Every organism in nature has its own place in nature. For an intelligent spider to evolve, it must find its place among prey, predators, and other environmental factors.
- There would have to be little competition. If a spider “meets its match” in the wild, it could be hard to establish a solid bloodline. Evolved spiders with larger brains would have to have brawn, too.
Were Spiders Smarter in the Past?
Insects, in general, were larger when dinosaurs roamed the Earth. That’s because the air was 31 to 35 percent oxygen––compared to the 21 percent it is today. This allowed prehistoric insects to swell to extreme sizes, with some species of dragonfly having two-and-a-half-long wingspans.
Whether prehistoric spiders were more intelligent than their descendants is another story. The fact is, scientists know very little about insects’ behaviors millions of years ago. They rely on the behaviors of insects today to speculate about the past.
Spiders and Their Brains: A Final Thought
A human brain will always outsmart a spider because of its size, processing power, and memory capacity. However, that isn’t to say that spiders are dumb and can’t survive on their own. Spiders have existed for 400 million years, and small-brained or not, they’re here to stay.
