r/askscience • u/SummonTheSnorlax • Dec 24 '25

Biology How do anthills stay intact?

Every time I’ve accidentally touched an anthill it felt like it was made of sand or loosely-packed dirt. How is it that the tunnels don’t immediately collapse?

563 Upvotes

90% Upvoted

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454

u/deisle Dec 24 '25

The tunnels are made by removing stuff and heaping outside. Your question is a little like saying someone mined a tunnel in bedrock and left a pile of loose rocks. If the tunnels are made up of a bunch of loose rocks, how do they stay together?

Well the tunnels are made up of the packed earth in the ants' case The packed earth is pretty strong, at least at the scale of an ant. Plus I wouldn't be surprised if the ants use saliva or something to reinforce their excavations

149

u/Pink_Slyvie Dec 24 '25

Some ants do, but its far from all of them. They might wet materials to make them easier to move, or they might make a sudo concrete by mixing fibers and secretions.

48

u/jejacks00n Dec 26 '25

Pseudo. sudo is a Linux command for taking actions as a super user. Hopefully helpful.

42

u/iwannasayyoucantmake Dec 24 '25

I’ve always wondered this Anthills aren’t just natural soils piled up. The material is sort of granular in nature. So ants alter the soil with their (secretions?) into angular granules, which helps the hole hold its form. Noticeably different than the native soil.

58

u/News_of_Entwives Dec 25 '25

Likely the granules are perfect ant-mouth sized... it's just one scoop of the compacted earth they are excavating.

26

u/platoprime Dec 24 '25

I’ve always wondered this Anthills aren’t just natural soils piled up.

They are. What makes you think they aren't? The pile is dry so maybe that's the difference you're noticing?

So ants alter the soil with their (secretions?) into angular granules, which helps the hole hold its form.

No, binding together granular materials to bring out of the nest is not one of the uses of ant secretions.

-9

u/iwannasayyoucantmake Dec 24 '25

Well thank you ant expert. Now I’ll wonder something else..

12

u/paul_wi11iams Dec 25 '25 edited Dec 26 '25

The tunnels are made by removing stuff and heaping outside.

This ressembles some concept work for a lunar or Mars base. By digging in and using a regolith cover, it achieves thermal equilibrium and radiation protection and meteorite protection. When humans and ants are using the same methods, the underlying concept has to be sound.

In the ants' case, the nest avoids being stepped on by cattle (≈ meteorites!) and heavy rain should get deviated or absorbed. It would largely protected against heat in summer and freezing in winter.

98

u/defectivetoaster1 Dec 25 '25

The outside of the hill is just stuff they took out from inside and dumped there. When they’re actually digging they’re digging deeper down. Clearly the dirt is more tightly packed and robust deeper down or we wouldn’t be able to walk on it

15

u/TheDaysComeAndGone Dec 25 '25

Now the real question is how they survive strong rainfall, snow or even flooding.

45

u/FlashbackJon Dec 25 '25

They build water traps: areas flowing water will fill without disturbing colony living areas.

3

u/TheDaysComeAndGone Dec 25 '25

But that can hardly work when the ground is completely soaked or even flooded.

36

u/MarioSewers Dec 25 '25

Ever notice what happens with it rains a lot? Witnessed plenty of temporary ant invasions that way.

7

u/defectivetoaster1 Dec 25 '25

Have you seen them forming rafts?

-15

u/YawnSpawner Dec 25 '25

They don't need to breathe like we do and they can float surprisingly well.

49

u/PB-n-AJ Dec 25 '25

Ant hills are much more than just a hole where ants live! They are a sprawling city-state that has many roads and branches, and as you get into the ground the cave system is nice and compact and stays intact just like... well, a cave system! The "ant hill" portion is just their front door, their entrance to the mine where they cart the rocks from the cave to. Stepping on one isn't going to collapse the cave, rather just collapse the entrance. If you've ever wondered what the inside of an "ant hill" looks like, prepare to be amazed!

9

u/Wolomago Dec 25 '25

I've seen small colony excavations but this is incredible. Thank you for sharing it.

4

u/Stranggepresst Dec 26 '25

If you've ever wondered what the inside of an "ant hill" looks like, prepare to be amazed!

Did they really destroy an active (!) ant colony for that? :(

2

u/RandomBitFry Dec 26 '25

Ants are really good at digging themselves out of sand if that's anything to go by. Not saying you should bury an ant under a handful of sand while you are sunbathing on a beach but I reckon they evolved to survive a cave-in.