Struggling jellyfish unite due to injuries
The comb jellyfish is expanding its reach, now prevalent in locations such as the Baltic Sea, Mediterranean, and Black Sea. A group of researchers may have unearthed the secret behind their rapid growth following a serendipitous find.
These jellyfish possess the extraordinary ability to merge into a singular organism within hours of injury, synchronizing their organ systems and muscles. This observation was made by a research team after conducting experiments on ctenophores, as detailed in the journal "Current Biology." As stated by the study's lead author Kei Jokura, "Our findings suggest that ctenophores may lack the capability to discern between themselves and others. Furthermore, our data indicate that two distinct individuals can swiftly link their nervous systems."
These discoveries stem from experiments involving the comb jellyfish (Mnemiopsis leidyi), a ten-centimeter-long species that originates from the western Atlantic but has since established a presence in various regions of the North and Baltic Seas, as well as the Mediterranean and Black Seas.
Injury and unexpected union
Previously, scientists had observed a notably large comb jellyfish in an aquarium displaying symptoms of a double digestive tract. Thisoddity could be the result of two injured jellyfish merging in the tank the previous day.
To substantiate this theory, the researchers attempted to replicate the phenomenon by severing parts of other jellyfish's outer lobes and placing the injured areas next to one another. The experiment resulted in nine out of ten successful unions, as reported by the team. The merged ctenophores survived the three-week experiment intact.
Within a single night, both organisms had combined. Stimulation of one lobe initiated a response from the other half, demonstrating that the nervous systems had successfully merged. "We were astounded to discover that mechanical stimulation of one side triggered a synchronized muscle contraction on the opposite side," said Jokura.
Digestive tract fusion
Further experiments revealed that the movement patterns of the newly formed organism were already 95 percent synchronized after just two hours. The digestive tracts of the precursor organisms also fused. The scientists fed the merged creature small fluorescent crustaceans through one of its two mouths on the second day. The food's path through the fused portion of the digestive tract could then be traced. The metabolic waste was subsequently excreted through both body openings, however at different times.
The spread of the comb jellyfish in European seas was reported by an international research team in 2018 in the journal "Global Ecology and Biogeography." Due to their competition with fish for food and their consumption of fish eggs and larvae, these creatures were described by the GEOMAR Helmholtz Centre for Ocean Research in Kiel in 2022 as "one of the most notorious invasive marine organisms."
The researchers attributed this fusion behavior to the jellyfish's lack of distinct individuality, suggesting that education about ctenophores should include their unique social structure. Furthermore, the success of the unions in the experiments highlights the potential for advancements in regenerative medicine, where injured cells or tissues could be merged for healing and survival.
