Amazing regenerating organisms

The idea of regenerating body parts is normally the stuff of books, movies and comics, but there are real-life animals that have this amazing ability. From regrowing missing limbs to repairing internal organs, these organisms continue to amaze us!

The amazingly regenerative Axolotl! Photo by carnifex82, reproduced under CC BY-NC-SA 2.0 license.

For many animals, the ability to repair body parts is a natural survival mechanism. Take for example the Axolotl (Ambystoma mexicanum), a salamander living in a small number of lakes in Mexico. Like many other salamanders, Axolotl are capable of fully regenerating missing limbs. Amazingly, the Axolotl can also repair much more than a missing leg or tail: experiments have shown complete repair of skin, spinal cords, and even organs! Scientists are obviously excited to understand how these sorts of regeneration can occur. In the United States there are approximately 1.6 million people living with an amputated limb, and many more that suffer from partial or complete organ failure. Understanding how animals are naturally able to regenerate might allow scientists and doctors to develop ways to mimic the process in humans. Below are a few animals that show incredible regeneration abilities.

The red-knobbed starfish (Protoreaster linckii).
The red-knobbed starfish (Protoreaster linckii).

Sea Stars – Sea stars, or starfish, can regrow missing arms, an ability they frequently use to escape from predators. When grasped, the sea star can detach its arm to escape. It is common to find sea stars that are missing multiple limbs. In fact, some sea stars can fully recover from a single arm – as long as that arm contains an intact central nerve ring.

Planaria are capable regenerators. Image by Eduard Solà.



Planarians – The humble planarian, a tiny flatworm commonly found in ponds and rivers, has an extraordinary ability to regenerate. Damaged planaria can regenerate fully from injury. Even more interestingly, it is possible to create entirely new planaria by removing small pieces which will then grow into a separate organism. It has been shown that fragment as small a 1/279 of a planaria can regenerate into an entire organism!



HHMI zebrafish
Zebrafish tail regeneration 1 and 10 days after injury. Photo from laboratory of Randall Moon

Zebrafish – Like other members of this list, Zebrafish (Danio rerio) are able to regenerate missing limbs, including very rapid regrowth of damaged fins. Research has shown that zebrafish can also regenerate tissue in the heart after injury. These results are exciting for patients suffering from heart attacks, which often result in damage and scaring in the ventricular wall.


These amazing animals show the power of self-regeneration in repairing the body after injury. Hopefully the lessons learned from studying this regeneration will someday be useful for treating human diseases.

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