One of nature’s most intriguing biological miracles is the amazing ability to regrow damaged or severed body parts. Animals including seastars, salamanders, planarians (flatworms), crabs and some fish are all capable, to varying degrees, of body part regeneration, ranging from limbs to tails, and on to even eyes and internal organs.
The process all starts with the clever cells we humans have when we’re growing in the womb: namely stem cells. Embryonic stem cells are those that do not yet have a speciality – that is, they can potentially become any cell, such as bone, muscle or nerve tissue.
Creatures that can regenerate new body parts remodel themselves into their original physical form by reactivating the cells near the wound site and instructing them to behave like stem cells. Some animals can retain bundles of these embryonic stem cells in their bodies, which – in the event of amputation – migrate to and proliferate around the wound where they get to work rebuilding the missing or damaged body part, just as if it were a growing foetus.