A science fact you hear tossed around is how ants are so incredibly strong for their size. Is this true, and if so, why? What about them gives them this physical power?
Does the same hold true for spiders, and so “explain” Spider-man’s strength?
It’s because doubling the size of a muscle only makes it four times stronger, but doubling the size of arms, legs, etc. makes them eight times heavier. If you make an animal larger and larger, the forces from its weight increase faster than the forces it’s muscles can produce. As you increase its size, eventually it will become a gigantic blob, where the strong muscles still aren’t strong enough to move the extremely heavy limbs.
But if you make an animal smaller and smaller, it’s weight decreases much faster than it’s muscle strength decreases. A typical ant can lift hundreds(?) of ants, but a typical human can only lift one or two humans.
BTW that is the “official” explanation for Spidey’s superstrength i.e. he has the “proportional strenth of a spider”
Sorry, but I have serious doubts about the accuracy of bbeaty’s answer. I think some of it is correct in principle, but on the whole it’s not that simple.
The main factor in an ant’s strength is that it has an exoskeleton. This provides both structural sturdiness and highly advantageous leverage for muscles.
All arthropods have exoskeletons and share the same benefits to varying degrees. Arthropods include insects, arachnids (spiders, scorpions, etc.), and crustaceans (crabs, lobsters, shrimp, etc.).
I don’t see how exoskeleton has anything to do with it. Okay, maybe a tiny bit 
Apes are much stronger than humans even in absolute terms, it has a lot to do with muscle structure.
bbeaty is right; things don’t all scale up and down in the same way; this is why 100 foot tall killer insects simply aren’t possible.
The endo/exo skeleton question can’t be addressed by comparing, say, ants with elephants.
You’d need to look at whether, say, a humming bird was stronger than a bird eating spider. That is, things of similar size.
(I don’t know the answer to that particular question.)
Certainly it is possible to compare, say, an elephant and a mouse (they are both land-based vertebrates); in proportion to overall size, the mouse’s bones and muscles are small and yet the mouse can run, jump, climb, change direction very quickly etc; conversely, the elephant’s bones and muscles are quite large in proportion to overall size and yet the elephant cannot jump, cannot climb and when it moves at speed (probably better described as a ‘lumbering charge’ than ‘running’), it cannot change direction rapidly.
After writing the above, I found this, which goes into a lot more detail about the way things scale up and down.
… the downward spiral of bodybuilding…?
But Bodybuilders add only a relatively small amount of size: they are still living inside a narrow range of human sizes. They are building the right kind of muscle tissue to enhance their strength.
In any event, simply because something is larger doesn’t mean it will be weaker; often the opposite. However, you can’t simply scale strength up or down like the OP implies.
In other words; absolute strength usually increases. Relative strength usually declines, as you get a larger organism. Eventually, unless you have some really awe-inspiring muscle material and design, you’re going to collapse under your own wieght. A 50-foot tall ant would simply pop like a balloon.
Heres a cite for you!
under “science” and and then “size matters”.
Other things change with scale too; the classic ‘bumblebee shouldn’t be able to fly’ argument ignores (IIRC) the viscosity of air, which is a far greater consideration at small scales, in fact some very small insects don’t so much fly as ‘swim’.
Ok, but what is inside those exo skeletons? I remember as a kid trying to dissect ants to see if I could discern little biceps, without much luck. It must take a reeeaally sharp knife. Are insect muscles, ligaments and tendons scaled down versions of what I would see in vertebrates?
IIRC Arachnids don’t have muscles inside their legs at all, the whole system is hydraulic. Not sure about insects.
Urban Ranger: It has a lot to do with it. As for apes, read Cecil’s column and you’ll note that he mentions leverage and muscle attachment, which is the key point with an exoskeleton.
Mangetout: Yes, surface to volume ratio is a factor, but in insects, long before gross size and weight present limits, their respiratory system is the key limitation factor on their size.
bare: They aren’t exactly the same, but they’re analogous. The really sharp knife you need is a microtome, to prepare tissue samples on slides for viewing with a microscope.
Mangetout: No, human-engineered exoskeletons often use hydraulic power, but the natural ones have muscles. That’s the meat in crab legs.
Go to
http://www.crc.losrios.cc.ca.us/~scotts/biology3/arthropods.htm and look under “Jointed Legs,” “evolution of jointed legs,” “3” for a brief discussion of the leverage involved.
Go to http://faculty.fmcc.suny.edu/mcdarby/Pages/SC%20139/Exams/139-4th-01-KEY.htm and look under “Short Answer,” “13” as well.
Similarly, from http://www.preston.k12.id.us/teachers/lbuys/invertnotes.htm:
“exoskeleton- skeleton on the outside, contains chitin, which is strong, flexible and relatively light weight
advantages- good protection, waterproofs, good leverage for muscles”
Think of insects legs and bodies as hollow tubes. Just as in bicycle frames and airplane fuselages, they offer a high strength to weight ratio. This keeps ants from getting crushed when supporting a hundred (?) times their weight. Then their somewhat different (from vertebrates) musculature combined with the leverage inherent in the exoskeletal design lets them manipulate that weight.
bbeaty’s response was not totally off the mark, the effects of scale are significant. But in the common concept of ants being so strong for their size, the exoskeleton is at least as significant.
“Ok, but what is inside those exo skeletons?”
Insect muscle contains arrays of actin and myosin that are very similar to what’s found in mammals. Here’s a picture.
Answer: Ants AIN’T so strong. I poked around to find what claims of ant strength are to explain what I mean, and found this site that already had an explanation of the scale effects:
As you might expect by looking at their spindly legs, ants aren’t really all that strong. The perception that they’re “stronger” is primarily a scale phenomenon.
So what you’re saying is that part of the weight is supported by the exo-skeleton as a framework and the muscle lifts the rest? The ant can lift heavy things because the skeleton is strong enough to take the weight? So how big could an ant get without sacrificing any strength?
Also, once I gave an ant a bowling ball…didn’t move it an inch.
Wuss.
Yeah, but an ant weighs much more than 3mg. A cc of water weighs roughly 1g. Say an ant is 6mmx3mmx3mm, which is 0.6x0.3x0.3 or 0.054cc. Water of that volume will weight 54mg. That’s like 12 times denser. What the heck is this ant made of, cotton candy?