Regeneration in Animals

 axolotl

The quest for survival has produced some bizarre evolutionary adaptations and regeneration is arguably of the most useful, but this adaptation is one that has considerably regressed along its way through evolutionary lines as body complexity increased. Various forms of regeneration, however, are still exhibited by many species, and even complex animals such as ourselves still maintain some basic and even latent regeneration capabilities.

Animals with the ability to regenerate limbs are some of the most extraordinary among us, and have captured the interest of biologists and scientists alike. We all know of lizards being able to grow back missing tails but many other species share similar traits. Insects and crustaceans are able to re-grow missing limbs too, but in arthropods regeneration is limited as its occurrence is linked to the molting process.

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Some primitive species are able to regenerate entire individuals from a severed limb or fragment such as sea stars and sponges through fragmentation, or the hydra through budding. But even more incredible is the ability to regenerate parts of complex structures such as organs and components of the nervous system. The Zebrafish is able to regrow its heart, retina, and other complex tissues. The Mexican Salamander, or Axolotl – an archetype for regeneration, is known not only to regrow missing appendages but can also regenerate damaged parts of its brain and spinal cord. In fact, an Australian research team is aiming to replicate the regeneration abilities of the salamander in humans using our own cells. The results could be groundbreaking.

In addition to replicating limb regeneration, research indicates that these remarkable creatures may also hold the secret to longevity within their DNA which is adapted to counter the aging process, giving some of these animals so-called biological immortality. Understanding this phenomenon could lead to further medical breakthroughs for us. The question is, do we deserve it?

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Sadly, the future of some of these animals may not be bright. Axolotls are on the critically endangered list due to habitat pollution. They are endemic to a small area around Xochimilco in southern Mexico where pollution of the Xochimilco Lake has become a major threat. According to the IUCN, habitat restoration efforts, in conjunction with conservation education and ecotourism initiatives are underway to alleviate the problem and hopefully reintroduce captive colonies into their natural habitat.

Unavoidably the elephant in the room is the controversial issue surrounding animal experimentation. Much is considered acceptable when it comes to medical research, however, the question is not simply what can be done for the benefit of mankind – but at what cost?

Indeed we have much more to learn from the weird and wonderful, but the priority as custodians should remain with the protection and ethical treatment of all species; as well with setting the precedent for future generations to respect, protect, and cherish.

TRIVIA: Sea stars, commonly referred to as starfish as they had originally been named, are in fact not fish. The term sea star was later allocated to the species which falls under the echinoderm phylum

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