Its really weird that spiders dont run away when they see a human. Aren’t they hundreds of times larger than they are? Why do they just chill and sometimes descend onto people or near a person. They can literally see other creatures even humans.
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Spiders dont recognize really large animals as predators. They will run or fight their natural predators which are much smaller
There’s a fight/flight response that is so archaic, most creatures show it. Some creatures freeze in place as a response to this, esp when they do not understand the ramifications of an encounter. If you do not know what might happen, you may run directly into more danger. Animals who are predators tend to freeze when confronted w unknown situations as they might be able to defend themselves, plus, it’s an ingrained behavior, as they tend to stalk and stay still more in the presence of other creatures.
Prey animals tend to have reflexes made to disperse and run from their predators so being in a unknown situation they are more apt to run, although not always. Prey animals who are preyed upon by ambush group predators will freeze more often in new situations as they have evolved to run into worst traps, etc.
Some good answers but I’ll add that creatures will often freeze because they don’t know if they’ve been spotted. It’s easier to detect something when it’s moving than when it’s still, especially if the thing has decent camouflage. You’ll never know how many spiders were right in front of you that you never noticed. But I bet you would have noticed if they suddenly scurried away.
It’s funny I read this today because last night I was laughing at a spider who had wedged itself half way under something so just its butt was sticking out. It probably knew some part of it was exposed but had no way of knowing if it had been spotted. I didn’t kill it by the way because many spiders are bros and I hope it’s helping me with my ant problem.
Spiders are working with tiny eyes and really tiny brains. It’s impressive how much performance they can get out of them (especially jumping spiders), but resolving a distant, large object and then distinguishing potential threats from other random large things is beyond their ability.
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Spiders, like all non-human organisms, are simply biological robots programmed by natural selection. They do not and cannot engage in reasoning, so it takes, in many cases, thousands of generations to reprogram them to respond differently than they already naturally do. But their programming is empirically successful, so spiders don’t run away as soon as they see a human because doing so would not be an adaptive behavior; they are more likely to pass on their genes by ignoring our presence than they are to do so by fleeing it. The relative difference in size might cause you to believe this is unintuitive because of the ease with which we can kill them when we want to, but it actually works the other way: they are more likely to see us than we are to see them, so even if every human unerringly killed every spider they notice, it is unlikely to make fleeing our presence an adaptive behavior.
Only wolf spiders and jumpers have good vision. All other spiders see light and dark. They don’t make out clear vision like we do. So they just see a big moving shadow. Learned that while working at a bug zoo with the arachnids for a summer.
In general spiders do not have good eye sight (jumping spiders and wolf spiders are some of the exceptions). That’s one of the reasons many hunt using webs – they use the vibrations to locate their food rather than their eyesight. If a spider is on your ceiling, the likelihood is that it can’t see you.
Even when they can, they don’t see the world the same way we do. Their eyes and brain are so vastly different from ours.
A lot of web spiders see only light and dark. So they basically can’t see you. They sense their world through their web. Tiny vibrations: food. Large vibration: animal to big to eat so run away.
Edit: I should add sometimes spiders like wolf spiders may appear to not only not run away but sometimes move towards you. When you are walking around you will disturb various bugs in the grass and that is what the spider is attracted to. So sometimes they use you to help root out their prey. But if you intentionally move real close the spider will then run away. I have had wasps use me in a similar way. There is an asian wasp in Texas that catch japanese beetle grubs. So they are always flying low and slow above the grass looking for prey. When I cut my grass I make their life a lot easier since they can see their prey better. So it will appear the wasp as coming after me if you look back while grass cutting. Not coming after you, just using you and are just following you, not attacking. They inspect the grass you just cut and follow you all around the yard. If you stop mowing, they will fly by or just fly elsewhere. Sometimes these bugs just find us to be darn helpful to them in finding their targets and aren’t interested in us otherwise.
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