It has long been known that many marine animals can regenerate themselves freely. This evolutionary attribute is being looked at more closely as a means to enhance human lifespan and develop new models for artificial tissue growth. 

A bevy of new studies on jellyfish and starfish, two invertebrates commonly known for their self-generating tactics, have emerged in recent weeks.

Starfish can reproduce both sexually and asexually by cloning themselves. They can also push foreign objects through their organs and out of their limbs. Jellyfish, on the other hand, can resimulate the lost symmetry of their bodies when tissue is lost.

Because starfish can choose whether to reproduce sexually or asexually through self-cloning, researchers at the University of Gothenburg wanted to investigate if the method of reproduction affects how long starfish can live.

What starfish can teach us about regeneration and living forever. Image 1.

By looking at star fish telomeres, which are repetitive nucleotide sequences placed at the end of chromosomes, researchers can tell how long species have lived, as telomeres shorten with age. They found that those starfish that had reproduced sexually were aging faster than those who had chosen to clone themselves. These findings were published in the journal Heredity.

In another experiment published in The Biological Bulletin, researchers at the University of Southern Denmark implanted micro-chips into starfish to monitor their bodies. They noticed that the chips kept falling out or disappearing, and eventually discovered that the starfish were expelling them from inside their organs.

If pushing out foreign objects through their skin isn't enough, jellyfish can go even further.

In a study done on moon jellyfish, or Aurelia aurita, researchers amputated several limbs of jellyfish and released them into their natural habitat. With previous knowledge of the species' immediate regenerative response, the aim to was to investigate the mechanism itself.

The jellyfish not only grew back all their limbs, but the new growths arranged themselves into the organism's original limb symmetry of eight arms in radial form. This suggests that jellyfish reorganize their own biological material every time they lose tissue.

Image: Michael Abrams and Ty Basinger. Image 2.Image: Michael Abrams and Ty Basinger

"This is a different strategy of self-repair," says Lea Goentoro, Caltech Assistant Professor of Biology. "Some animals just heal their wounds, other animals regenerate what is lost, but the moon jelly ephyrae don't regenerate their lost limbs. They heal the wound, but then they reorganize to regain symmetry."

The self-cloning, symmetrical regeneration, and expulsion methods of these invertebrates can be useful in advancing techniques for growing or regenerating biomatter. Scientists are hopeful that this kind of research will pave the way for more experimentation in the field.

Cover image: Wikimedia Commons