The jellyfish with a nervous system that is causing a shiver in the scientific community

Comb jellies may be too small to even cause ripples in the water as they swim, but their unique features are creating shockwaves in the scientific community.

A beautiful marine creature with a jelly-like body surrounded by iridescent combs. The most likely candidate for the earliest branched-off animal lineage. And now, an impossible nervous system. Comb jellies may be too small to even cause ripples in the water as they swim, but their unique features are creating shockwaves in the scientific community.

A recent study, published in Science, looked closely at the nerve-net neurons of comb jellies and found that instead of being connected by synapses – junctions between neurons in all other animals, including humans – they are continuously connected by a single plasma membrane.

Comb jellies, or ctenophores, belong to phylum ctenophora, and are one of the oldest animal lineages with a defined nervous system. They are quite hard to culture in the lab, however, yet Pawel Burkhardt managed to do just the thing in his lab at the Michael Sars Centre at the University of Bergen, Norway.

“This was something that all came together, step by step. We were able to basically disentangle the nervous system,” Dr. Burkhardt told The Hindu.

He had collaborated with Maike Kittelmann of the Oxford Brookes University in the U.K. previously for a study, published in Current Biology in 2021. In this study, they examined a single neuron in the nerve-net using high resolution electron microscopy. They found that the neurites – the branches from the neuron that form synapses – were all interconnected by a single plasma membrane, a feature not seen in the neurons of other animals.

For the new study, they wanted to see how a single nerve-net neuron could make connections with other nerve-net neurons. When they observed the microscopy images of the different nerve-net neurons together, they were taken completely by surprise.

“We expected synapses,” said Dr. Kittelmann. “We went in there to find the synapses between the nerve-net neurons, but we just couldn’t find them, because they aren’t there.”