Animals use active processes to obtain nutrients for their biological needs. Movement is supported by the nervous system, made up of individual neurons. The nervous system transmits signals between the sensory and motor system, allowing the ability to sense, move, breathe, and feed. The transmission of signals occurs via tiny gaps between neurons, where chemical or electrical signals transfer nerve impulses in one way. The electrical synapse is a cell association between two nerve cells where ions are used to transmit nerve impulses rapidly. In the latter case, neurons release chemicals that must travel across this gap to stimulate the post-synaptic receptors.
Recent work has shown that Comb jellies have a cobweb of neurons rather than synapses, with a unique, fused structure pictured above. These ancient animals are called comb jellies because they swim using rows of beating, hairlike combs. Comb jellies fused nerve net represent long, stringy neurons sharing a cell membrane. Comb jellies or ctenophores are similar to jellyfish. Still, the enigmatic phylum is one of the earliest, perhaps the most ancient animal group, to branch off the animal tree of life.
Reference article:
P. Burkhardt et al. Syncytial nerve net in a ctenophore adds insights into the evolution of nervous systems. Science. Vol. 380, April 21, 2023, p. 293. Doi: 10.1126/science.ade5645.
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