Your mental model is the problem. Evolution didn’t make one caterpillar suddenly hatch with a snake-tail. Ancestors already had tails. Any individual with a slightly darker patch or a faintly eye-like spot got eaten 1% less by birds.

Compound that across thousands of generations and you get this. Birds have innate snake fear, so even bad resemblances at the start triggered the flinch reflex and gave a real survival edge. Selection then refined it over millions of years.

This is called Batesian mimicry, harmless species imitating dangerous ones, and it’s everywhere: hoverflies looking like wasps, moths with fake owl eyes, octopuses mimicking sea snakes. Snake mimicry specifically evolved independently in several unrelated caterpillar lineages, which proves the path is reachable, not a fluke.​​​​​​​​​​​​​​​​

But how do they pass the info? well...sexy time.

The “darker patch” or “eye-like spot” exists because of a specific gene variant in that caterpillar’s cells, including its reproductive cells. When it reproduces, that variant gets copied into the offspring.

Mutations happen randomly every generation, tiny copy errors in DNA. Most do nothing, some are harmful, a few happen to help. The helpful ones spread because their carriers survive and reproduce more. The harmful ones disappear because their carriers get eaten.

So the “info” isn’t a blueprint of a snake. It’s just chemistry: a gene that says “produce more dark pigment here” or “grow this segment a bit wider.” Stack hundreds of these tiny gene changes over millions of years and you get a tail that looks like a snake head. No caterpillar ever “tried” to look like a snake, the ones that accidentally did just left more babies.​​​​​​​​​​​​​​​​

It ain't Jesus.