<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=192888919167017&amp;ev=PageView&amp;noscript=1">
Monday, March 18, 2024
March 18, 2024

Linkedin Pinterest

Researchers discover how jellyfish regain symmetry after loss of limbs

By
Published:

Some animals that lose a limb simply regenerate a new one. But that’s not what moon jellyfish do when they lose an arm or two. They work with what they’ve got.

These translucent creatures actually reorganize their remaining arms to regain their lost symmetry.

CalTech researchers describe “symmetrization,” a previously unknown process, in a recent article in the journal Proceedings of the National Academy of Sciences.

Symmetry is vital to moving and eating for jellyfish. When moon jellyfish lose an arm, a physical process forces them back into shape.

“They rely on the mechanical forces generated by their own propulsion machinery, which is their muscle and the viscoelasticity of their jelly material,” said Michael Abrams, a CalTech graduate student and a lead author of the study.

Researchers studied about 500 organisms from four species. They anesthetized juvenile jellyfish, called ephyra, and amputated one to seven arms. While it took just a few hours for the wounds to heal, the jellyfish didn’t create new cells. But two to four days later, they were once again symmetrical. What’s more, the injured jellyfish that reorganized themselves matured into adults. The 15 percent of the young jellies that didn’t reorganize successfully didn’t mature normally.

“It broadens our understanding of the self-repair mechanism,” Abrams said, adding that it’s unclear what those implications could be. “So maybe we think about self-repair a little differently. It’s not always about regeneration and regaining lost parts.”

To test this, the researchers added muscle relaxers to the injured jellyfish’s seawater. That slowed muscle contractions, so it took them longer to reorganize. The opposite effect happened when researchers reduced the magnesium levels in the water.

“With each pulse of the arm, they contract their arms,” Abrams said. “That pulls their material in, and that means there’s higher pressure of material that pushes against itself and repels against each other.”

The jelly material facilitates the process, he added.

One co-author, Chin-Lin Guo of Academia Sinica in Taiwan, helped develop a mathematical model to demonstrate how the jellyfish managed to force themselves back into symmetry through muscle contractions.

One researcher compared the process to removing a front wheel from a four-wheel car, Abrams said. The car needs balance to move, so it would be like moving the remaining front wheel to the middle of the vehicle.

Self-repair is crucial to these creatures; an estimated 33 to 47 percent of seafloor invertebrates are injured at any given point in time, according to a 2010 study published in the journal Integrative and Comparative Biology.

Other researchers could take this principle of reorganizing and apply it to their work.

“It’s not out of the realm of possibility that we could try to build something that takes into account the mechanism of symmetrization,” Abrams said.

Loading...