The Central Nervous System
The nervous system of Nautilus contains a much larger number of neurons than is found in any noncephalopod mollusk. Many of the neurons lie in peripheral ganglia, especially those of the tentacles and the brachial nerve cords in the arms. On the other hand, there is a great concentration of neurons to form a “brain,” which is composed of cords around the esophagus. The nervous organization thus consists of peripheral reflexes for detailed actions subordinated to a brain devoted to control of the whole animal. Cephalopods have probably used this system since the Cambrian Period (≈ 500 Ma), and it was probably in large part responsible for their early success as dominant carnivores of the seas.
KeywordsCambrian Mollusk Paleontology
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