how can an ant carry something twice its size and weight?

Question

like a leaf...or bread, or rice

Answer 1

It has to do with the fact that ants are really really small. The amount of weight a structure (such as an ant's exoskeleton) can support is roughly proportional to its cross-sectional surface area, which is in turn proportional to the square of the linear dimension. However, the weight of the structure itself is proportional to its volume, which grows as the cube of the linear dimension. So if x is the length of the ant, m is the weight it can carry, and M is the weight of the ant, then m/M ∝ x²/x³ = 1/x. Since ants are small, x is small and therefore 1/x is large, which is why ants can carry many times their own body weight. But this isn't unique to ants -- anything that size could support several times its own body weight, and if we scaled you down to the size of an ant you would be able to lift several thousand times your own body weight (since your body was built to support itself at much larger scales). Conversely, if we scaled an ant up to the size of a human, it is unlikely that it would even be able to stand up.

Answer 2

It has to do with the ant's surface area to volume ratio. The ant has a very low volume, but a high surface area due to its head, thorax, abdomen and legs. It's exoskeleton makes it incredibly strong, and allows it to carry things much larger and heavier than itself. I believe I read somewhere than an ant can carry some objects up to 40 times its own body weight!

Also, because of the physiology of an ant[ and other arthropods], you won't have to worry about gigantic ants attacking the city anytime soon like in those old horror movies...at that size, they're bodies would be much to heavy to be supported by their own legs, and therefore is a limiting factor in how big insects can actually get!