When injured, some jellyfish regenerate limbs. Some return to their polyp state and being maturation over again.
The ability to heal is necessary for jellyfish because they are a food source for sea turtles. In a jellyfishes lifespan they constantly need to heal from injuries and loss of limbs.
A recent study of moon jellyfish explains a newly discovered method of self-repair. It is called “symmetrization” and refers to the process in which moon jellyfish rearrange their existing limbs to account for the lost symmetry.
This new finding has redefined what is known about this species of jellyfish and their abilities to recover and heal.
The discovery was made by researcher Michael Abrams of the California Institute of Technology. Abrams states:
“We’ve now observed another self-repair mechanism. It kind of broadens our definition, a little bit, of self-repair.”
Abrams and his professor, Lea Goentoro, did not set out to study moon jellyfish. Originally they were going to study the immortal jellyfish who earn their name based on their self-repair process*. While they were waiting for the immortal jellyfish specimens to arrive at their lab, Abrams began trial on the moon jellyfish.
To study these jellies more in depth, the researchers began with juvenile jellyfish, called Ephyra. Ephyra possess eight symmetrical arms attached to a disc-shaped body which make them ideal for regeneration study subjects.
They severed the arms of several moon jellyfish, cutting between two and seven arms off. The moon jellyfish were then placed back in seawater where their regenerating habits could be monitored.
The researchers findings demonstrated that the moon jellyfish quickly healed and then began reorganizing their limbs to form better symmetry.
Over three quarters of all the jellyfish observed performed symmetrization. The jellies that were given an anesthetic were not able to regain symmetry because they could not complete the motions necessary in the process of symmetrisation. The ones who failed to regain symmetry grew extra stomachs and dropped to the bottom of the tank.
So why is symmetry needed by these jellyfish? Abrams explains:
“Jellyfish move by ‘flapping’ their arms; this allows for propulsion through the water, which also moves water — and food –past the mouth. As they swim a boundary layer of thick fluid forms between their arms, creating a continuous surface that aids their paddling motion. And you can imagine how this paddling surface would be disturbed if you have a big gap between the arms.”
Jellyfish may not have eyes or ears, a nose, or even a brain…but they are still classified a marine animal.
Perhaps it’s my ignorance on the subject but I am not sure I can get behind a study that involves forceful amputation of a live animal even if it does result in interesting findings.
*Immortal Jellyfish – When injured, they convert back to their polyp stage. The ability to do this an infinite amount of times essentially makes them immortal.