The crustacean nervous system consists basically of a brain, or supraesophageal ganglion, connected to a ventral nerve cord of ganglia, or nerve centres. In primitive forms, like the anostracan fairy shrimps, the brain has nerve connections with the eyes and antennules, but the nerves to the antennae come from the connecting ring around the esophagus. In more advanced forms the antennal nerves originate in the brain. The first ventral nerve centre under the esophagus (subesophageal ganglion) is usually formed by the fusion of the ganglia from the mandibular, maxillulary, and maxillary segments, but other ganglia may be incorporated. Often there ...(100 of 7175 words)