The brain is the most complex structure in the known universe and it evolved more than once
How, Why and When neurons and brains evolved is one of the greatest unresolved mysteries. According to our team research (Prof. Leonid Moroz Lab research), the answer exists in the sea, and in open oceans. It seems paradoxical for many people but the shortcut to understand our memories and cognition, to cure neurological disorders, to establish regeneration medicine of the future, and even paths to immortality go through the sea. There is no other way around it - do we like it or not.
Pulling the plankton net on board Vinson of Antarctica
The secret holds by enigmatic plankton species, known as comb jellies or ctenophores. These beautiful and fragile creatures are pelagic, which means that they only live in open waters and most of these species are inaccessible for land laboratory research. They are predators too.
We even do not know exactly how many ctenophore (and other) species exist in our oceans and biology for most of these species still remains elusive. Yet, these aliens of seas can be efficiently collected during marine exploration such as the current transatlantic trip on Vinson of Antarctica, which retraces the famous Darwin voyage more than 180 years ago.
The emerging data from just a few ctenophore species (which already have been investigated using modern physiological and genomic technologies), provided provocative and surprising solutions for the very designs of neural systems. Yes, ‘designs’ are plural! Recent research of our lab (Prof. Moroz lab at UF) suggests that neurons evolved more than 3 times and complex centralized brains evolved more than 20 times! (Ref #1-2) Unexpectedly, the genomic research also indicated that muscles and many other animal features evolved independently in ctenophores (Ref #3). With such unusual molecular designs, ctenophores are remarkably different from the rest of marine animals and earned their name and true Aliens of the Sea!
Image of the ctenophore
The more surprising finding is that ctenophores might contain not one, but two neural systems and perhaps an elementary brain (Refs #4-5). Even more surprising is that some of the ctenophores can efficiently regenerate neurons and the elementary brain (also called the aboral organ) within a few days, and heal the wounds within hours.
Even during the first weeks of the Ocean Genome Atlas Project (OGAP) voyage and plankton sampling (near Canary and Cape Verde islands) provided unique samples of comb jellies (see photos) for deeper genome-scale analysis and further deciphering the origins of neural organization and elementary cognition.
References:
1. Moroz LL, Romanova DY, Kohn AB. 2021 Neural versus alternative integrative systems: molecular insights into origins of neurotransmitters. Phil. Trans. R. Soc. B 376: 20190762. https://doi.org/10.1098/rstb.2019.0762
2. Moroz LL, Kohn AB. 2016 Independent origins of neurons and synapses: insights from ctenophores. Phil. Trans. R. Soc. B 371, 20150041. doi:10.1098/ rstb.2015.0041
3. Moroz LL et al. 2014 The ctenophore genome and the evolutionary origins of neural systems. Nature 510, 109–114. doi:10.1038/nature13400
4. Norekian TP, Moroz LL. 2020 Comparative neuroanatomy of ctenophores: neural and muscular systems in Euplokamis dunlapae and related species. J. Comp. Neurol. 528, 481–501. doi:10.1002/cne. 24770
5. Moroz LL. 2015 Convergent evolution of neural systems in ctenophores. J. Exp. Biol. 218, 598–611. doi:10.1242/jeb.110692
Dr. Leonid L. Moroz
University of Florida, USA
