Eli5 Why are ants so resistant to dying by falling?
In: 18
They are so lightweight and so large, that they become their own parachute. Their terminal velocity (the max speed at which they can fall through the air) is low enough that they can survive the landing.
If you throw then down in a vacuum, they will get too fast at some point and die on impact. Of course, they wouldn’t survive in a vacuum in the first place, but just imagine a little space suit for them 🙂
It’s not so much that they are resistant to dying by falling. The ant’s mass is so small compared to the body’s surface area that they fall extremely slowly on average about 6.4 km/h or 1.78 m/s for its terminal velocity.
You can compare that to an adult male human which has a terminal velocity of 200 km/h or 55.56 m/s.
The ants achieve this by fanning our their legs to slow them down similar to how a squirrel can theoretically survive a fall from any height because of their size, mass, and fur.
They fall very slowly because they’re so light that just the air itself slows them down a lot.
This means they don’t take much or any damage when they land.
Terminal velocity is the fastest something can fall. Some things like ants and squirrels and mice have a terminal velocity that isn’t fast enough to kill them.
Our good friends over at Kurzgesagt made an excellent video on exactly this topic. I suggest checking it out along with just about all of their other videos.
There’s a great old paper on this by JBS Haldane, called [On Being the Right Size](https://www.phys.ufl.edu/courses/phy3221/spring10/HaldaneRightSize.pdf). It’s a pretty easy read, so anyone interested in this stuff might want to take a look at it.
Here’s a relevant passage discussing the force of gravity
>To the mouse and any smaller animal it presents practically no
dangers. You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes. For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal’s length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force.
>An insect, therefore, is not afraid of gravity; it can fall without danger, and can cling to the ceiling with remarkably little trouble. It can go in for elegant and fantastic forms of support like that of the daddy-longlegs.
Because they’re small. It’s the same reason any small object doesn’t get damaged when you drop it. If you pick up something ant-sized, or as small as you can get (maybe a paperclip, a button, or a grain of rice), hold it high and drop it on the floor it won’t be damaged. But if you did the same with something bigger it would be damaged.
They just don’t have enough weight to do any serious damage when they hit the floor. If you the floor hard you might hurt your foot because of the weight of the rest of your body squashing your foot into the floor. An ant doesn’t have that since its entire body is much less high than your foot.
Just some FYI to add. Squirrels also have a survivable terminal velocity. I believe they are the largest mammals that can do it if I remember correctly
At the size of an ant, gravity is more of a suggestion this is why so many Insects have the ability to fly to them. The air feels more like water
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