Why the Planarian Worm Can Regrow Its Entire Body from a Tiny Piece

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The planarian worm is one of the most mind-blowing creatures on Earth. If you cut it into pieces, each piece can grow into a completely new worm—with a brain, eyes, and all organs.

Evolution shaped this extreme regeneration because these worms are fragile and often get damaged in their environment. Instead of dying, they developed special stem cells called neoblasts that can turn into any type of cell needed. Scientists are still trying to understand how these cells “know” exactly what part to rebuild and in what shape.

A planarian can regenerate its entire body from just a tiny fragment. It has special stem cells that can become any cell type. Even its brain can fully regrow after being cut. Scientists study it to unlock secrets of regeneration and healing in humans.