These strange sea creatures can fuse together and turn into an animal if injured

Time does not heal all wounds. If you are an injured comb jellyfish, you may just need another of your species to blend in with.

That’s what biologists at the University of Chicago’s Marine Biological Laboratory found when they examined samples of a species called Mnemiopsis leidyiwhich is also known as wart shoulder jelly. Native to the western Atlantic Ocean, these jellyfish have the uncanny ability to fuse together after being injured, fusing not only their outer tissues but also their nervous and digestive systems. These findings could have major implications for the study of human regeneration.

This discovery was prompted by a chance observation. One day after collecting some comb jellyfish from the wild, the researchers noticed that one of them had strange characteristics. This type of comb jellyfish usually has an apical organ, a sensory organ that many invertebrates have, but this specimen had two. It also had two aboral ends: in other words, it had two edges, which is strange again.

Biologists theorize that jellyfish (singular) were once jellyfish (plural) and fused together as a way to survive injuries. To satisfy their curiosity, they partially cut off the lobes of other jellyfish and placed them in a tank. As reported in Current biologyin 9 out of 10 cases, pairs of comb jellyfish were combined into a single entity. In all nine cases, the thawed animals survived the full three weeks in their holding tanks. Since the duration of the experiment was three weeks, it is possible that they survived even longer after they put themselves together.

The process was quick. After only one hour, the movement of the transplanted lobes was synchronized. An hour later, the overall motion of the lobes in the compound was 95% synchronized. The biologists wrote that after just one night, the boundary between the composite jellyfish had “solidified” and the outermost layers of tissue appeared “seamless.” Even nervous systems showed signs of gelling. When biologists pressed a lobe into a jellyfish, it made one lobe belong to the other.

“We were surprised to find that mechanical stimulation applied to one side of the fused ctenophore led to a coordinated muscle contraction on the other side,” said Kay Jokura, a postdoctoral researcher who worked on the study, in a statement.

Even the digestive system functioned as one. In a video of one of their experiments, one side of a molted jellyfish can be seen digesting a brine shrimp injected with a fluorescent substance. As the jellyfish begins to digest it, the fluorescent particles can be seen flowing towards their attached compatriot lobe, which expels some of the waste.

“The transport of digestive particles through fused canals suggests that such systems are functionally coupled and not just physically connected,” the biologists wrote. However, the fact that only one side of the waste is discarded may indicate that the two jellyfish do not actually become the same animal. The scientists added: “The lack of simultaneous excretion suggests that the transient nature of the anus and its ultradural rhythm are independently controlled in molted individuals.”

There is still much to learn about how mollusk jellyfish work and why this strange behavior helps them survive. In the paper, the scientists said it was not clear how neural systems could connect to each other, something they hope to learn more about with further experiments.

This discovery could go beyond describing a new survival mechanism. Jellyfish appear to lack a system for omnidirectional recognition, or the ability to tell whether cells are their own or someone else’s, Jokora said. Allorecognition is a key component for medical procedures like organ transplants, so these exotic sea creatures, who may be big fans of the Spice Girls, could hold the key to advances in immune system and regenerative therapies.