What is the nervous system of crustaceans: closed or not closed?

Crustaceans belong to a large group – arthropods. Accordingly, for them, the nature of the nervous system is the same as for other representatives.
The nervous system is not closed and is conventionally divided into three sections: the paired supraopharyngeal ganglia, the nerve ring and the abdominal nerve chain. The difference in the nervous system is the fusion of the ganglia.



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