The fact that animals of a certain size can no longer exist is essentially a geometric phenomenon.
Let’s just imagine some animal and make it 10times that big.
E.g. a human being.The original is 2 m tall, weighs 100 kg. After the enlargement, it is 20 m tall (attackof the 20-meter woman (1993) – Wikipedia 🙂 ), but all proportions remain.What happens?
The weight of man is proportional to its volume, assuming that the density of all human beings is the same.
Volume V results in V = C * t * b * h. C is a constant that takes into account the shape of man. The other values are depth t, width b, and height h. Because the proportions are maintained, C remains the same at magnification, while the other values increase by a factor of 10.
The weight G results in G = V * density.
Then the new volume results after the enlargement to
Vneu = C * 10 t * 10 b * 10 h = 1000 * C * t * b * h = 1000 V
This means that the weight of humans would have increased by a factor of 1000 after enlargement by a factor of 10.This would mean the weight of the 20 m human being at 100,000 kg = 100 t. It would weigh as much as the largest sauropods and half as much as a blue whale.
The strength of a muscle depends primarily on its cross-sectional area, if other influencing factors, such as the training state, are left out.
Double cross-sectional area, double force. Assuming that a muscle, such as the biceps, has a circular cross-sectional area, its cross-sectional area A to A = D2 / 4 * pi results. During magnification, the diameter increases by a factor of 10. This results in the cross-sectional area Aneu after the enlargement to Aneu = (10 D)2 / 4 * pi = 102 * D2 / 4 *pi = 100 * D2 / 4 * pi = 100 A.
Since the cross-sectional area has increased by a factor of 10 by a factor of 100, this means that the strength of the muscle has also increased by a factor of 100.
However, the weight of humans has increased by a factor of 1000.This means that the ratio of force to load has deteriorated by a factor of 10. In practice, the 20 m man would feel like the 2 m man he would weigh 1000 kg. He could no longer stand up because he did not have enough strength.
The same view also applies to the skeleton, to bones and tendons, whose strength would not increase to the same extent as the weight that they would have to bear.In a simple fall, the 20 m man would break all the bones and with almost every movement the tendons would tear.
Each cell needs a certain amount of oxygen to live.
Since the number of cells that need oxygen is proportional to the weight at magnification, the oxygen required increases proportionally to the weight.
Oxygen is transported through the blood in the body.This means that with a magnification of a factor of 10, one needs 1000 times the volume flow Q of blood.
The required power P for this is proportional to the product of volume flow Q and pressure loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The pressure loss is proportional to the length and flow velocity to the square according to flow technique – formula collection and calculation programs and inversely proportional to the diameter of the blood vessels.As a result, the pressure loss increases by a factor of 100. In practice, it is lower, about 40, because the influence of the pipe friction number was not taken into account in this estimate.
If you want, you can experiment with this calculation program: Calculate flow values.
Since Q increases by a factor of 1000 and a factor of 40, the required power increases by a factor of 40,000.However, the performance of the heart enlarged by a factor of 10 only increases by a factor of 100. So the heart would have to perform 400 times relative, which is impossible.
Here, one would have to counteract by disproportionately increasing the blood vessels and the heart and slowing down the metabolism in order to ensure the oxygen supply.Or, if necessary, several hearts.
The 20-metre-high must also be pumped to the height of the 20 m person to ensure the supply of the brain.
This means that the pressure must be applied 10 times to pump the blood so high, in addition to the increased pressure difference from point 3. This would bring the vessel walls to their load limits and possibly cause them to burst.
If the 20 meter person bends down and then rises again, the problem would be a sudden loss of pressure in the brain, which would lead to unconsciousness.The giraffe therefore has backflow flaps in its heaps to prevent this, e.g. when it rises up at a water point after drinking.But giraffes also only get about 6 m tall and not 20.
Elephants already have the problem that they have to eat most of the day to get enough food for their large bodies.
Sauropods had the same problem and solved it by simply squeedying down their leaf food, unlike elephants that still chew. Due to their long necks, they were able to stand somewhere and simply devoured everything in the vicinity. So they didn’t have to move much. But also elephants avoid hills, for example, because it would cost them too much energy to climb up to eat there(TIERE: Elephants hate hills).
It would therefore be problematic to provide a 20 metre person with adequate food.A bunch of fish, as in the Godzilla film by Emmerich, would be just a hors d’oeuvre for the lizard. Better would be a bunch of whales…
Due to the enormous length of the nerve pathways, there are problems with the signal times.
The stimulus transmission takes place at approx. 100 m/s. To transmit a signal from the foot to the brain, it would take a man of 20 m to take 0.2 seconds. Until a reaction occurs, at least 0.4 seconds. That would make the 20-metre man very slow in his reaction.
Surely there are other reasons why you can’t make an animal any size.But I’ve already written a little novel and I want to leave it at that.
Godzilla is, of course, even bigger than the 20-metre man.About 50 m in the old Japanese movies, up to over 100 m in the film of our Roland Emmerich.
With these body sizes, the observations made are even more true, as for the 20 m human being.Sure, evolutionary adjustments can still use certain reserves to enlarge an animal, but at some point it will be over. Either the force becomes a problem, the stability of the skeleton, the oxygen supply or the food intake. Or all together.