You know, in general it’s called mimicry. But how does it work even though all these creatures only perceive their surroundings with the eyes and so on. Like…just how it knows the way these creatures should be changed to be less visible.
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This is flawed logic, nature didn’t do anything. The creatures that blended in with their environment weren’t seen by predators and therefore survived to reproduce, leading that trait to carry forward.
Nature doesn’t “do” anything, things just happen in response to environment.
Natural selection. The stickbug that looks less like a native stick gets eaten and the one that looks more like a native stick stays hidden and can reproduce.
Everything is a random mutation.
But it makes sense that animals with the best mimicry will survive long enough to procreate. We can actually observe that with European moth Biston betularia that has two distinct forms (spotted white or melanistic black). It can be observed that before industrial revolution the white spotted specimens were more common as they could blend with shrubs and on tree bark and hide from predators, but now it’s the black form, because the barks became darker and shrubs less common.
Initially all you need to do is to be slightly closer in colouration and shape to hide from predators and increase your chances of survival. When all the obvious creatures are removed from the gene pool pressure is then on the remaining ones and as new mutations occur those which enable a greater degree of hiding survive and those that don’t become lunch, the process takes thousands or even millions of years before the current forms are so well hidden. Camouflage can also happen in plants as well as animals. https://youtu.be/9rOURRXEbk0
These creatures don’t *choose* to look this way, it’s evolution.
Basically take creature A, some random bug. A new bird moves to town that *loves* to eat this bug. One day a baby creature A kind of sort of looks a bit flatter, a bit more like leaf. The bird doesn’t see it at first and eats some other creature A. Creature A’s babies all look flatish too. Over time, if this repeats basically only Creature A’s babies survive and now all of that bug look like leaves, the rest were eaten by birds. The creature doesn’t know it looks like a leaf, it doesn’t know what a leaf is and it might not even know what a bird is. It just goes about’s life and survives.
Another example of how this might work is imagine there is a blight on the tree that Creature A looks like the leaf of. Suddenly there are no more of those leaves and suddenly they really stand out, suddenly it’s open season on Creature A’s leaf family. Then Creature B is born, which is a mutated Creature A that looks like a slightly different type of leaf. *That* new creature survives. Maybe all the Creature A’s die out, or maybe they all only survive in a random forest untouched by the blight. Now you have Creature A *and* Creature B living at the same time apart from each other, that’s the creation of a new species.
This process as I’ve simply described it is the basics of what we’d now call “Darwinian Evolution”, it’s not perfect for describing everything in nature but it forms the basic thesis of how evolution works. I recommend picking up “On the Origin of Species” by Charles Darwin if you’re interested.
Similarly you can have something called “Convergent Evolution” where something is so wildly useful random animals all start doing it too. For example octopodes and chameleons developing color changing skin – they aren’t *related* to each other, they didn’t share a color changing ancestor. They just both independently discovered that’s pretty nifty.
Another similar example is called “carcinisation”, or “looking like a crab”. Basically being crab shaped is so wildly useful as a body form tons and tons of animals around the planet ended up looking like crabs. Not saying they are related, it’s just that many creatures all discovered that being crab shaped is super useful.
Let’s take a deer as an example.
One day, long ago there was a four legged creature. It looked much like a deer, but shorter and chunkier and had no antlers.
We’ll call it a Deern’t.
These creatures weren’t so good at fighting, so predators ate them in droves.
Further, they weren’t so good at running either.
This lead to fierce competitions for mates, headbutting and attacking each other.
One day, a really wierd deern’t is born. It has these wierd mutations that cause some of the hairs on its head to grow super wide. I mean really wide. Like what the heck is this big patch of keratin, ew.
Well, those wierd dumb gross keratin mutations make headbutting way safer. They also grow long and sharp and pointy which makes them great weapons. This Deern’t becomes a god among its kind, staving off every hornless deern’t and spreading it’s mangled but beneficial genes through the population.
We’ll call this step, The Derr.
The Derr begin to throve, but they are still very bad at running away.
Well, one day some Derr is born with just… FREAKISHLY long legs i mean what the EFF are those STILTS attached to you?
But it turns out, those longer legs mean it only has to run faster than the other Derr. As the slower Derr die off, the long legged, faster Derr gets to mate and spread its genes, making many long legged derr.
Eventually, with tons of these random small changes happening via natural selection, we get things that just work. “Designed” by billions of years of trial, error, loss of what doesn’t work, and survival of what works.
So in the terms of a stick bug… One day a bug with a longer body was born. It died less often. The longer bugs that moved in specific ways died less than the shorter bugs. Eventually stick bug.
It’s random. Some animals get born with random mutations that change how they look. It might make them look more like the environment, it might make them bright orange, it might make their heart explode and kill them. If **a random mutation happens to, by complete coincidence, make the animal look slightly more like the environment**, then that animal is less likely to be seen and eaten. In turn that means it’s more likely to survive and reproduce, passing on its altered appearance.
But isn’t a random mutation more likely to make an animal look less like the environment? Yes! And all those animals with random mutations making them stick out more are all more likely to be eaten, and therefore *less* likely to reproduce and pass on their appearance.
Over millions of years, where each individual that *just randomly happens to* look a little more like the environment has a slight survival advantage and slightly more offspring, then it adds up. The genetic lines that look more like the environment are favoured, those that are less camouflaged die out.
there’s a lot of survivorship bias here. Animals are so well adapted it looks like evolution must have known or planned their current shapes. But no, it’s totally random – the animals that exist today are the descendants of those who *just happened to* have a useful appearance. All the unlucky families that randomly mutated a less useful appearance have died out, leaving us with the descendants of the ones that happened to have more useful mutations.
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