“At first, I thought that we discovered something entirely new. That nobody knows that ctenophores can fuse with each other. But then, we started doing literature surveys and found a paper published by B.R Coonfield in 1937 where he showed the results of grafting experiments done with ctenophores,” Jokura said.
Coonfield, a scholar at the Department of Biology at Brooklyn College, performed those experiments to prove that ctenophores possessed a special kind of symmetry in their anatomical features.
Coonfield used grafting, a technique used mainly in botany to merge two different plants into one, to see if the anatomy of ctenophores was indeed symmetrical. He didn’t think too much about their ability to survive the grafting, merely making a note that it occurred. Jokura, on the other hand, made it the main focus of his work.
Synchronizing comb jellies
First, Jokura and his team selected 10 pairs of healthy-looking ctenophores, cut them, and held them close together. “The individuals were immobilized, with little room for movement and a small gap between them. Gradually, we saw that gap closing, and finally, the individuals came into contact with each other,” Jokura said.
First, the comb jellies merged their membranes and epidermal parts, which constitute a two-cell-deep barrier protecting the inside of the animal from the environment. Once this was complete, their nervous systems started to merge, too. “The nerves got connected and electrical coupling happened. The muscle contractions started to synchronize. After 30 minutes, they were synchronized [to] 50 percent. After two hours, they were synchronized completely,” Jokura explained.
But not every system in these comb jellies merged seamlessly. “The pooping time depends on the individual, as each individual has its own metabolism that dictates when you want to poop,” Jokura said. The digestive systems in a fused comb jelly kept working seemingly independently of each other, with food going to either one or the other mouth and the waste being extracted from two separate anuses at different times.