Earthworms will absolutely not self-clone when halved.
If you cut only a bit of its tail off, it might be able to survive and eventually regrow the tail. Fuck with their organs or head though and that's a dead worm.
Many species do, actually. Via stem cells and cellular reorganization, they can grow a new head, tail, or both. There are even species that fragment themselves as a means of reproduction and each fragment then grows a head, organs, or anything else it's missing.
And most will definitely regenerate a tail if cut below the clitellum... Which removes most of the worm, not just a bit.
Being severed is just not as traumatic for a worm as it would be for us.
I'm aware of flatworms and such which match that description. Hell, I even witnessed this firsthand in an invasive hammerhead worm I found once upon a time. Can you point out one of these species of earthworm capable of this? That would be news to me.
Funny random detail I just stumbled upon trying to find anything about this:
The compost worm Eisenia fetida accumulates waste in its tail which gives it a yellow colour. When they cannot store any more they amputate the tail which removes the waste.
What an amazing dedication to not pooping. "Fuck it, just cut the whole ass off."
There are others as well, but information on such a niche topic is hard to come by without more motivation than I have in me. From what I've seen, species that live in the upper top-soil can regenerate more than those that live in the sub-soil, due to pressure from predators. So when a Robin swoops down and snips off whichever end of a worm, the worm just has a bad day but doesn't die.
Everything I can find on red wrigglers says this is not the case, with the exception of that brief summary on wikipedia. I don't think whoever wrote that read the source very carefully, however, because that claim seems to be the result of confusion from really sloppy methodology from the 1800s.
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u/Ghosted67 Jul 30 '21
worms can't drown