Photo by Uda Dennie
It’s spring here in the northern hemisphere, and with spring comes a surge of critters. I’ve seen lots of spiders around my home lately, so I thought I’d take some time to talk about spiders and why they’re cool. Arachnaphobia warning, but also if you’re not too sure about spiders, you might want to give this one a read. Spiders are awesome and they have no interest in chasing or biting you at all. And the more you know, the more you’ll appreciate them!
First of all, what exactly makes something a spider? You’ve probably heard people say, “They’re not insects, they’re arachnids!” — but let’s get into that. Insects and arachnids do have a lot in common — they’re invertebrates (they don’t have a skeleton inside), they’re arthropods (they do have a skeleton on the outside), and they’re generally small and make a lot of people say “Ew!” when they see one. But that’s about where the similarities end. Arachnids like spiders have more limbs, more eyes, fewer body segments, and (usually) venom of some sort. And as for what makes something a spider specifically is if it can make silk.
Let’s take a look at the parts of a spider.
Image from Spidentify
8 legs, which the spider controls with hydraulics instead of muscles
Cephalothorax, or head
Abdomen, or butt
2 pedipalps, more limbs that evolved into sensory feelers
Chelicerae, or combo jaws and fangs that deliver venom
A bunch of eyes that don’t usually see very well
And of course, spinnerets, or the bit where silk comes out
Photo by Matt Crane
The silk is worth an entire post of its own, but here are the basics: It’s made of liquidy protein chains that solidify as soon as they’re out of the spider. Those proteins are really valuable, so it’s not uncommon for spiders to eat their own webs to recycle them. They make a bunch of different kinds of silk for different purposes, but we humans are most interested in the one called dragline silk, because it’s super strong and lightweight — ideal for things like towing cables or bulletproof vests. Unfortunately, it’s really difficult to farm spiders for their silk, because unlike commercial silkworms, captive spiders tend to eat each other. Of course, they didn’t evolve silk for us, but for themselves. Spiders use silk to hunt for food, but also to protect their eggs and to travel through the air — sometimes for hundreds of miles.
Ballooning spiders use electricity and wind to balloon. Footage from Science Magazine
So far we’ve covered general info about spiders, but now I want to show you some of my favorite weird little guys.
Diving bell spiders live underwater in dense silk domes. They swim up to the surface, trap air in their abdomen hairs, and transfer the bubbles into the web to make a cozy home full of breathable air. Photo from National Geographic
Trapdoor spiders wait for something tasty to come by their burrow — then they pop out and nab it. They’re also highly relatable with how they prefer to be left alone. Footage source unknown, but found here (heads up for slight spider jumpscare)
Ogre-faced spiders don’t wait for things to land in their webs. Instead, they bring their webs — or nets — to their food and trap it. Footage from Rhagodes
Ant-mimicking spiders… well, mimic ants. Different species have evolved to look, act, and even smell just like certain kinds of ants so they can infiltrate colonies and feast on their hosts. Photo by David Wirawan
Jumping spiders have excellent vision (as far as spiders go) and fast reflexes, which they need for stalking and pouncing on prey. They’re a lot like tiny cats. Photo by Kaldari via The Atlantic
Bolas spiders don’t make webs, but instead use sticky silk globs to “lasso” passing moths. They lure in dinner by mimicking the moth’s preferred pheromones. Footage from BBC’s Life in the Undergrowth, via globalzoo
Cyclosa spiders, a.k.a. trashline orbweavers, a.k.a. decoy spiders, fill their webs with bits of detritus and arrange it to look like a bigger spider. The real spider is just above the bottom middle leg. Photos by Lary Reeves
You might still be on the fence about spiders, which is understandable. Arachnaphobia is super common, and even those of us who like spiders can get freaked out when one suddenly drops on you from the ceiling while you’re sitting in your favorite rocking chair and makes you jump up and shriek and send the cat that was on your lap flying across the room. Hypothetically speaking, of course. But spiders are also fascinating and really important! As key predators in their ecosystems, they keep pests under control, on the order of an estimated 400-800 million tons of insects every year. Plus there’s their silk and just their inherent value as creatures.
So next time you see a spider, leave it alone, or at least gently move it back outside. I don’t think I’d call them friends, exactly, but they do at least make for good neighbors.
Photo by Scott Linstead