Normally when a jellyfish loses a limb, say to the jaws of a hungry sea turtle, it simply regenerates the lost appendage, no big deal. However, a Caltech research team has been studying a certain jellyfish species that doesn't regrow its limbs but rather rearranges the remaining ones to maintain symmetry. They think that this body-modifying trick could one day help robots repair themselves after similar injuries.
In a paper published June 15th in the Proceedings of the National Academy of Sciences (PNAS) the team described its work with the moon jellyfish. They amputated the various numbers of limbs from anesthetized jellies and then monitored their recovery. While the jellies healed in a couple of hours (as they normally do), the team noticed that rather than beginning to regrow their limbs the jellies instead shifted their remaining appendages around to restore their symmetry. What's really wild is that mechanical forces created by the jelly's own muscle contractions appear to be behind its reorganization.
"This is a different strategy of self-repair," Caltech assistant professor of biology Lea Goentoro said in a statement. "Some animals just heal their wounds, other animals regenerate what is lost, but the moon jelly ephyrae [juveniles] don't regenerate their lost limbs. They heal the wound, but then they reorganize to regain symmetry."
This discovery could lead to new advances in robotics. "Symmetrization may provide a new avenue for thinking about biomaterials that could be designed to 'heal' by regaining functional geometry rather than regenerating precise shapes," Goentoro continued. "Other self-repair mechanisms require cell proliferation and cell death—biological processes that aren't easily translated to technology. But we can more easily apply mechanical forces to a material." Soon, injured robots may not drag their broken limbs behind them like this little guy, but simply rearrange their other legs instead.
[Image Credit: Getty Images/Vetta (top); Caltech (inline)]