As the creator of several tarantula blogs and groups, I get asked some pretty interesting questions about tarantulas and spiders. One that came up quite recently was this: Do spider poop? Do they pee?

That’s a REALLY great question – and one that many people wouldn’t know unless they’d had firsthand experience owning a tarantula or other arachnid. Unfortunately, very little is known and publicized about the way the bodies of arthropods work, and although the tarantula hobby is growing with great speed now, most of us are still desperately looking for answers to many burning questions (like do spiders poop lol).

Do spiders poop?

Well, I can tell you from firsthand experience that YES, spiders poop! I know this due to my own experiences with Spidey, my Chilean Rose Hair and first tarantula. Blinky, my Arizona Blonde, ALSO poops (and these poops are kinda big for such a little spider!)

But if you didn’t know what you were looking for, you might miss a spider poop entirely. Tarantula poop tends to look like smearable white stuff until it dries – in fact, in my opinion it kind of resembles a nicer version of bird poop. The consistency and appearance seems similar (I’ve never touched it, though – so I’m just talking about appearance alone). Some tarantula owners, however, have not been so lucky:

Many tarantula owners have been “blessed” by their spider children taking a poop on them.

The process of spiders pooping is actually pretty interesting! Check out this amazing footage of a tarantula making a nice poop (you’ll see what I mean about the resemblance to bird poop). This is a great video because there are so few resources documenting how arachnids excrete waste!

Am I the only one who thinks that’s kind of precious?! What a nice healthy spider poop – 10/10! The nice thing about tarantulas is that they usually are very tidy creatures. So very often they will designate only one part of their tank as their bathroom and only poop there. Or they will limit their poop to their walls. However, some tarantula owners report that certain species are very messy and will spray their poop all over their tank. I have heard this behavior is popular among the avicularias.

Now I SHOULD mention that tarantulas do have one VERY curious habit – they absolutely LOVE to go to the bathroom in their WATER DISHES. No one knows why – but it’s a common observation amongst tarantula owners. I mean, look at how much fun this NAUGHTY baby is having!

By the way, when their poop touches water, it looks pretty different – it kind of resembles tiny white pebbles. So if you notice something like white stones in your spider’s water dish, don’t worry – it’s probably just spider poop.

Now, onto the other bathroom duties: Do spiders pee?

This was harder to answer because while I’d seen Spidey and Blinky poop before, I wasn’t too sure about pee. I did a little bit of digging around and found this, which seems to suggest that spiders’ poop and pee is kind of mixed together:

Spiders have structures designed to get rid of nitrogenous waste. These are called malpighian tubules and function in a manner similar to our own kidneys. Spiders don’t produce urine like we do, but produce uric acid, which doesn’t dissolve in water and is a near-solid. Spiders have this alternate form of waste because they can’t afford to lose as much water as we do. These malpighian tubules drain into an pouch attached to the digestive tract (called a stercoral pocket) so the uric acid waste from the “kidneys” is combined and eliminated together with solid waste from the digestive tract. In this sense, spiders don’t deposit separate feces and urine, but rather a combined waste product that exits from the same opening (anus). 

It also seems they don’t have urinary tracts like we do, either – it all goes out the same way.

So I guess spiders neither poo or pee – they peep!

Here’s another fascinating response about spider poop and pee from Blaine Hebert, M.S. Biology, California State University Northridge:

So, while we still may not understand everything about the way spiders poop and pee, I think this is a good start! I hope this gave you something fun to think about 🙂

By the way, check out my new tarantula magazine for more cool spider stuff:

I’m putting out issues every 2 months! If you’d like to be a part of that, you can visit the magazine’s Patreon page to subscribe or make a submission! You can also contact me at theavenmag@gmail.com for more info!

If you want to learn more about tarantulas, feel free to check out my big tarantula guide (I talk about lots of tarantula facts and enclosure/care tips). You can also get free tarantula tips by signing up for my newsletter or subscribing to my YouTube channel! I release new tips every Tuesday for Tarantula Tuesday! And I also sell some pretty cool tarantula t-shirts, if I do say so myself 😉

Featured image via Alrighty Spidey blog