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The Strength of Moon Jellies' Muscles Help Them Perpetually Self-Heal

ByAbbey InterranteNOVA NextNOVA Next

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While the field of robotics has advanced greatly in the last decade, scientists have struggled to create robot that can reliably heal themselves. Robots with soft structures, in particular, are prone to damages when navigating complex environments. Some engineers have tried giving robots “bio-inspired” characteristics, like the ability to regrow damaged parts or heal wounds, in order to counter the risk.

The task isn’t an easy one—most self-repair mechanisms rely on new growth. But scientists have just discovered that the moon jellyfish,

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Aurelia aurita , self-heals by undergoing a very different process: it adjusts the structure of its body.

moon-jellyfish_2048x1152
Just keep swimming.

The moon jellyfish is made of a gelatin-like material and can get injured rather easily, like other animals similar to it (in fact,

one study estimated that 35 to 47% of seafloor invertebrates are injured). They also have radial symmetry, which means their bodies are organized around a single axis—when cut in half in any direction through the middle, the resulting two pieces are mirror images of each other. In order to move efficiently through the water, moon jellyfish need to hold this symmetry in place. So when a moon jellyfish loses a limb, it contracts and expands its body in order to re-establish the radial symmetry it needs to survive in the wild, according to Michael Abrams of the California Institute of Technology, who was the lead author of a study published June 15 in Proceedings of the National Academy of Sciences .

This process is called symmetrization, and it’s a natural part of the jellyfish’s lifestyle, even when uninjured; as a moon jellyfish flaps its arms, its body deforms and takes in nutrient-rich water. At the completion of this “pulse,” the jellyfish returns to its original state.

Here’s Sabrina Imbler, writing for Scientific American:

The researchers found that the muscle contractions exerted by each pulse of the jellyfish with a missing limb forced its other arms to space out equally. The sudden crowding sensation of its remaining arms caused the jellyfish to push its limbs away from one another and toward the empty space, thus forming a more stable configuration. ‘In one pulse, it may look like it’s going back to its original form,” Abrams says. “But that pulse over thousands of times makes symmetry.’

Imagine a wagon that has lost a front wheel. Without changing the placement of the remaining three wheels, the wagon would be stuck. Centering the remaining front wheel, however, would rebalance the vehicle as a fully functional wheelbarrow. Same function, different body.

If scientists are able to mimic moon jellyfish’s ability to self-heal through symmetrization, they might be able to create a robot that can move efficiently and fix itself, without needing to keep the additional supplies on hand. The moon jellyfish adapts to its new body and recreates the structure it needs through a pre-existing muscle function. A robot that uses this process wouldn’t need to develop anything new—it would just restore the symmetry it needs to complete its role.

Learn more about bio-inspired technologies with "Making Stuff: Wilder," streaming online.