Now, we can scale up, or down, it doesn’t matter… but pound for pound, which creature would own the earth if everything was the same size?
In my opinion, I think a ‘daddy long legs’ (cellar) spider would kick everyone’s ass. It’s already capable of owning pretty much everything within its size range, and I can’t see a mammal, bird or reptile being quick enough to take it on if reduced down to their size.
In other words, I think spiders would be top of the food chain, and in particular, that.
I don’t think a daddy longlegs has much strength relative to size. Put it in a fight against a similar sized wolverine, and that spider would be ripped to shreds in no time.
That made me wonder if there was a Marvel character named "Daddy Longlegs.’ Turns out that there is, but he is apparently the only one who hasn’t fought Wolverine.
Myself, I wouldn’t want to encounter a 180-pound wheel bug.
IIRC from my biology courses, the exoskeleton of a man-sized arthropod would be so heavy that the creature would barely be able to move. My guess would be some kind of large cat would be at the top of the food chain.
I guess it depends on how you define size; overall volume or weight. If its by weight then birds of prey would become truly terrifying. Right now I know several 15-20 lb cats that have been disappeared by owls. Even if you think those owls were on steroids they were probably in the 5-10 lb range so they’re easily running twice their weight class so a 200 lb owl would be able to eat anything it own size. Of course it would be 40 ft tall with a wing span of 100 ft so not quite in the same volume category. If they were the same volume were only talking maybe a 10’ wingspan and 4’ tall but they’d only weigh 10 lbs and would be no threat to most sized up mammals.
If we’re going by volume I’d nominate the wolverine. Right now they’re 42" x 18" and weight 71 lbs on the large size. So they would stretch to 72" X 31" and 280 lbs and that’s a lot of pissed off muscle. That said I’d still take the 200 lb owl against the 280 lb wolverine.
Amoebas and bacteria have a lot going for them. Fortunately, their reproduction is limited by their food supply, so we won’t have their population doubling every twenty minutes.
Rotifers are scary.
But, ultimately, it’s humans. Even at stone-age tech levels, we can plan, scheme, make fire, and fire projectiles. A lot of us are gonna die, but we’ll win. Slowly.
ETA: Of course, in such a world we would not have evolved in the first place: no mammals would have, and probably no megafauna as we know them.
More generally, size is one of the easiest things to change by selection pressure. Animals are the size they are because it gives them specific benefits that other sizes wouldn’t necessarily have. Sure, our 1920’s style HISTA* ray might allow something to “skip” inconvenient middle sizes to a new size where it would excel, but I’d put my money against it.
An animal whose size is vastly out of sync with the sizes that it evolved to is likely going to be severely crippled, not given superpowers. Thought experiment: You can increase or decrease your OWN size to any reasonable level. Aside from minor tweaks around the normal human range, are ANY of them going to make you a better combatant?
Firing projectiles is key. I think some snakes and insects can fire venom, but the exoskeleton problem is still there, and so is the fact that snakes might not have evolved at all in a world of giant bacteria.
However, if this happened suddenly tomorrow-- we woke up and the insects were huge, our pet cats were huge, etc., we’d lose a lot of people, but I think we’d overcome with our arsenals.
A coiple of things would have to happen-- we’d have to get over worrying about making species extinct, and kill all the giant predator birds, and different countries would have to get over themselves and cooperate even if it meant turning all our stockpiled weapons away from other people and on our new animals.
One thing that might help us is that we might luck out and after averaging viruses with blue whales, the size everything came out to be would make us smaller than we are now, but maybe not small enough not to be able to operate our weapons. If that happened, though, we might be screwed.
Most thing on earth are bugs and probably trillions of bugs on earth and if all the bugs where scaled up by tomorrow there probably would be more bugs than land on earth for the bugs. You would need bigger earth for all the bugs.
There probably would be very little humans left alive if that happen and be more like mad max society or walking dead society, where most of human race is dead and living in fortified building hardly going out side for much of any thing.
Just think of walking dead not dead zombies but very big bugs every where. There would be not much left of human race. The human race will be very close to extinction.