January 01, 2017 at 12:07PM
"The comb jelly, a primitive marine creature, is forcing scientists to rethink how animals got their start." #readingToday

Moroz's primary evidence for an independent origin of neurons in comb jellies comes from their unusual nervous systems. "The ctenophore's nervous system is dramatically different from any other nervous system," said Andrea Kohn, a molecular biologist who works with Moroz. Comb jellies appear to lack the commonly used chemical messengers that other animals have, such as serotonin, dopamine and acetylcholine. (They do use glutamate, a simple molecule that plays a major role in neuronal signaling in animals.) Instead, they have genes that are predicted to produce a slew of neural peptides, small proteins that can also act as chemical messengers. "No other animal except in this phylum has anything like that," Kohn said.

Did Neurons Evolve Twice? | Quanta Magazine