When moon jellyfish lose a limb they regain symmetry in a surprising way

Researchers at Caltech University wanted to study the process of self-repair in moon jellyfish. To do this, they cut off some limbs and waited. What happened next surprised them, because many marine invertebrates are known to regenerate limbs that they have lost. But not the moon jellyfish. Instead, the moon jellyfish did something very different. 

Michael Abrams, the lead author of a new study published this week in the journal Proceedings of the National Academy of Sciences, tells As It Happens co-host Carol Off how it all got started: "In the beginning I did a kind of old-school experiment, like people have been doing in marine biology for hundreds of years, where you just sort of amputate things and see what happens."

Abrams adds: "We thought they would regenerate...but what ended up happening was they started reorganizing and moving their arms around their bodies. And I quickly realized they were not doing what we expected. I've never heard of anything like this before. As soon as we cut them and put them back in the water they would start moving again and pulsing around and then over a couple of days they would change their body symmetry to regain the radial symmetry that they had lost."

Abrams explains to why it's so crucial for moon jellyfish to regain their radial symmetry: "It is really important for this organism's ability to swim and to eat. If you can imagine something where you have one-half of the body generating currents while swimming and the other half not, because you've taken off the arms on that side, you can imagine how it's not going to be able to swim very well. And their swimming brings water, and therefore food, passed the mouth and that's very important for their feeding."