Organ and Organ Systems in Animals — Bio Zoology STD 11 — Question

The bibbed mass of nervous tissue called supra-pharyngeal ganglia lies on the dorsal wall of the pharynx in the 3 segment. It is referred as the brain. In the 4th segment, the sub-pharyngeal ganglia is found. The brain and the sub-pharyngeal are connected by a pair of circum-pharyngeal connectives. The double ventral nerve cord runs backward from the sub-pharyngeal ganglion. The brain and other nerves in the ring integrates sensory inputs and command muscular responses of the body.