On a summer night in 2023, In Jokuraa researcher in marine biology, ran into the laboratory of the Woods Hole Oceanographic Institute in Massachusetts. He carried with him an unusual find: in a beaker, a gelatinous mass seemed to be the result of the union of two jellyfish penalty. What began as a curiosity would soon become a scientific discovery that challenges the most fundamental notions of biology.
These specimens, known scientifically as Mnemiopsis leidyiwere in the tanks on the first floor of the laboratory. At first glance, the merger of two organizations did not seem possible. However, upon observing that the two specimens swam and reacted as a unit, the researchers began to wonder: how is it possible for their systems to integrate in such a way? The story that emerged from this moment opens a window into the deeper past of life on Earth and raises philosophical questions about the nature of biological identity.
What makes comb jellyfish a focus of interest is that they could be the oldest animals on the planet. Their ability to fuse and survive as a single organism not only intrigues scientists, but also questions biological boundaries that were thought to be unbreakable.
Las comb jellyfish They are not common jellyfish. They belong to the edge Ctenophorawhose name means “comb bearers” in Greek. This group is distinguished by the cilia arranged in rows that they use to move in the water, a unique characteristic in the animal kingdom. Unlike common jellyfish, comb jellyfish do not sting and are not phylogenetically related to them.
What makes them even more fascinating is their age: according to biologists, the ctenophores They are among the first animals to evolve in the history of life on Earth. “They represent a unique opportunity to study fundamental aspects of the functioning of the nervous system,” he explained. Mariana Rodriguez-Santiagoco-author of the study and a postdoctoral fellow at Colorado State University.
Beyond their biological attributes, these creatures also stand out for their adaptability. Another recent study published in the journal PNAS showed that M. leidyi can revert to an early state of development after experiencing stress. This level of evolutionary flexibility could be key to their survival in changing environments.
The experiment that Jokura and Rodriguez-Santiago carried out consisted of joining pairs of comb jellyfish together after making small incisions in their bodies. The result was surprising: nine out of ten pairs were completely merged. Not only their bodies were united, but also their nervous and digestive systems, creating a functional organism that shared movement and nutrition.
The fusion process was monitored by time lapse images. During the first minutes, the muscle contractions of the organisms were independent. However, after an hour they began to synchronize, and in less than two hours they were functioning as a single entity. “The rhythmic movement came together so quickly that it took us by surprise,” said Jokura, lead author of the study published in Current Biology.
Additionally, to test the integration of their digestive systems, the researchers fed fluorescent shrimp to one of the fused organisms. The food moved through the digestive canals of the first specimen and crossed into the second, where it was expelled as waste. This finding revealed a complete internal coordination.
One of the most interesting questions that arose from this discovery was how comb jellyfish lack the mechanism of allorecognitionwhich allows organisms to differentiate between their own cells and those of another. This mechanism, common in humans and other animals, is responsible for rejecting foreign tissues, as occurs in the rejection of transplanted organs.
In comb jellyfish, this absence could be an evolutionary advantage. The merger allows them to form a largest and most functional organismimproving your chances of survival in a hostile environment. “It is fascinating how these animals overcome the barriers that normally protect organisms from external threats, adapting in a completely different way,” added Rodriguez-Santiago.
Beyond the biological, researchers believe that this phenomenon raises questions about the nature of identity and consciousness in living beings. Jokura expressed interest in exploring how neural networks integrate after fusion: “We could be talking about something similar to a fusion of thoughts.”
Comb jellies not only reveal secrets of ancient biology, but also offer a platform to explore current concepts about adaptation, simple nervous systems and the limits of individuality. Their fusion ability could inspire research in areas such as bioengineering, tissue regeneration, and understanding primitive nervous systems.
