I was casually watching videos of king crabs, lol, when I saw this video of a chef cutting just the legs of the crab and waiting for it to grow another set. It was a brilliant idea. But it makes me wonder what other species of animals share the same ability.
In: Biology
Because the crabs who can regrow limbs survived better in their environmental niche. This is a feature of many insect-like or lizard animals, but not something that mammals can do.
When most creatures are developing (in an egg, womb, whatever) their cells have the ability to “be anything”. Like a brain cell, a skin cell, an eye cell, a toe cell, whatever, they can be anything and this point the creature is typically just a ball of goop. We call these “be anything” calls ‘Stem Cells’.
At some early point the stem cells start getting jobs, they lose the “Be anything” ability and differentiate into eye cells, brain cells, kidney cells, etc. As those cells start increasing and everyone gets a job, you get a baby creature.
The problem is a kidney cell *can’t* just go back and become a brain cell in a pinch, once a cell differentiates, it can’t turn into something else. This is why if I cut off your toes, you just have no toes anymore. You body knows how to “have toes” and how to “be toes”, but it’s forgotten how to “make toes”.
Some animals though can create new stem cells if they want. If I cut off the leg of a starfish, fresh stem cells start flooding the wound and after checking out the damage the stem cells turn into new-leg cells and the star fish regenerates.
Not tons and tons, but lots of animals can do this. Some lizards can regrow a lost tail, starfish and most bugs and seabugs (crabs, lobster, shrimp, are really just ‘seabugs’) can regrow. Heck, some jellyfish can convert their entire body back into stem cells when they get too old and “re-birth” themselves into a baby, meaning they are essentially immortal.
Humans can’t do it though and we have very limited abilities to study human stem cells because we’d need to get them from a human fetus and there are obvious reasons why we limit that kind of access.
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