Table 2.

Comparison of main features of the nervous system in Bryozoa

	Phylactolaemata	Cyclostomata	Gymnolaemata	Reference
digestive tract	mostly nerve plexus	few neurite bundles, on anal and lateral sides of the foregut	few neurite bundles on anal side of the foregut	29, 32, 67, this study
lophophoral base	circum-oral nerve ring	circum-oral nerve ring plus incomplete outer ring	circum-oral nerve ring plus incomplete outer ring (trifid nerve)	29, 30, 32, this study
cerebral ganglion/brain	with cavity	without cavity, plus lateral ganglia	cavity in few ctenostomes, missing in cheilostomes	30, 32, 60, this study
tentacle innervation*	6 tentacle nerves	4 tentacle nerves	4 tentacle nerves	26, 29, 32, this study
tentacle sheath	mostly diffuse nerve plexus	two neurite bundles from cerebral ganglion	two mixed bundles	29, 67, this study
body wall	nerve plexus	mainly circular neurites in epithelium of membranous sac	separate parietal neurite bundles	29, 59, 67, this study
apertural/orificial innervation	radially via duplicature bands and vestibular wall	radially via attachment organ and vestibular wall	via few parietovaginal bands or distinct aperture	61, 67, this study
serotonergic nervous system	concentrated in cerebral ganglion, thin bundles in circum-oral nerve ring, regular perikarya at lophophoral base	concentrated in cerebral ganglion, thin bundles in circum-oral nerve ring, three oral perikarya	concentrated in cerebral ganglion, thin bundles in circum-oral nerve ring, regular perikarya at lophophoral base with three oral perikarya including ‘serotonergic gap’	31, 33, this study

*possibly peritoneal neurites or subperitoneal cells not considered