Researchers have made an unexpected finding regarding a specific type of comb jelly, known as Mnemiopsis leidyi. This species has the remarkable ability to combine, allowing two separate jellies to merge into a single entity after sustaining an injury. Following this fusion, they quickly align their muscle movements and connect their digestive systems to share nourishment.
In a report published in the Cell Press journal Current Biology on October 7, researchers announced their surprising discovery that a particular species of comb jelly (Mnemiopsis leidyi) can amalgamate, enabling two individuals to transform into one after experiencing an injury. Subsequently, they swiftly synchronize their muscle contractions and unify their digestive systems to facilitate food sharing.
“Our research indicates that ctenophores may not possess a process for allorecognition, meaning they lack the ability to differentiate between themselves and others,” explains Kei Jokura from the University of Exeter in the UK and the National Institutes of Natural Sciences in Okazaki, Japan. “Moreover, the findings suggest that two distinct individuals can quickly blend their nervous systems and share electrical signals.”
Jokura and his team made this discovery while observing a group of comb jellies kept in a seawater tank in their laboratory. They noticed a particularly large jellyfish that appeared to have two rear ends and two sensory organs called apical organs instead of the usual single structure. This raised their curiosity about whether this peculiar jelly had formed from the fusion of two injured individuals.
To investigate, the researchers excised parts of other comb jellies and placed them in pairs next to one another. Remarkably, they found that this method was successful 90% of the time, with the injured jellies merging into one and surviving for a minimum of three weeks.
Further examination revealed that after just one night, the two original jellies completely fused, with no discernible separation remaining. When the team gently poked one part of the combined jelly, the entire entity responded with a noticeable startle, indicating that their nervous systems had merged as well.
“We were amazed to see that applying mechanical pressure to one side of the fused jelly caused a synchronized muscle contraction on the opposite side,” said Jokura.
In-depth analyses revealed that the fused jellies exhibited spontaneous movements for the initial hour. Following this, the timing of muscle contractions in each segment began to harmonize. Within just two hours, an impressive 95% of the muscle contractions of the fused jelly were perfectly synchronized. The researchers also examined the digestive system, noting its fusion as well. When one mouth ingested fluorescently tagged brine shrimp, the particles moved through the shared canal. Ultimately, the jelly expelled waste through both of its openings, though not simultaneously.
The researchers acknowledge that it is still uncertain how the merging of two individuals serves as a survival tactic. They propose that future investigations will enhance understanding, with potentially significant implications for regenerative studies.
“The mechanisms of allorecognition are linked to the immune system, and the fusion of nervous systems relates directly to research on regeneration,” Jokura states. “Understanding the molecular processes behind this fusion could further essential research fields.”
