Myogenic activity and serotonergic inhibition in the chromatophore network of the squid (family Ommastrephidae) and (family Loliginidae).

Seemingly chaotic waves of spontaneous chromatophore activity occur in the ommastrephid squid in the living state and immediately after surgical disruption of all known inputs from the central nervous system. Similar activity is apparent in the loliginid , but only after chronic denervation of chromatophores for 5-7 days. Electrically stimulated, neurally driven activity in intact individuals of both species is blocked by tetrodotoxin (TTX), but TTX has no effect on spontaneous wave activity in either or denervated Spontaneous TTX-resistant activity of this sort is therefore likely myogenic, and such activity is eliminated in both preparations by serotonin (5-HT), a known inhibitor of chromatophore activity.