Researchers reporting in Cell Press’s journal Current Biology have made the surprising discovery that a transparent jellyfish-like creature (Mnemiopsis leidyi), also known as the “sea nut” can fuse, so that two individuals quickly become one in following an injury.
They quickly synchronize their muscle contractions and join their digestive tubes to divide the food.
“Our findings suggest that ctenophores may lack an allorecognition system, which is the ability to distinguish between self and others,” says Kei Jokura of the University of Exeter, UK, and the National Institutes of Natural Sciences in Okazaki , Japan.
“Furthermore, the data imply that two separate individuals can rapidly merge their nervous systems.”
Jokura and his colleagues made this observation after keeping a population of seawater in the laboratory.
A survival strategy
They observed an unusual individual that appeared to have two dorsal parts and two sensory structures known as apical organs instead of one. They wondered if this unusual individual came from
To find out, they removed partial lobes from other individuals and placed them close together in pairs. Turns out, 9 times out of 10, it worked. Wounded individuals became single, surviving for at least 3 weeks.
Further studies showed that after a single night, the two original individuals became one, with no apparent separation between them, writes .
When the researchers poked a lobe, the entire fused body reacted with a prominent response, suggesting that their nervous systems were also fully fused.
Potential implications for regenerative research
“We were amazed to see that mechanical stimulation applied to one side of the fused ctenophore resulted in a synchronized muscle contraction on the other side,” said Jokura.
More detailed observations showed that the fused ctenoptera had spontaneous movements within the first hour. After that, the timing of the contractions on each lobe began to be more present. After just two hours, 95 percent of the fused animal’s muscle contractions were fully synchronized, they reported.
They also looked closely at the digestive tract to find that and . When one of the mouths ingested fluorescently labeled brine shrimp, food particles made their way through the fused canal. Finally, the comb jelly expelled the waste products from both anuses, although not at the same time.
Researchers say it remains unclear how fusing two individuals into one works as a survival strategy. They suggest that future studies will help fill the gaps in understanding, with potential implications for regenerative research.
