NEURONAL BASIS OF HUNTING AND FEEDING-BEHAVIOR IN THE PTEROPOD MOLLUSK CLIONE-LIMACINA

The pteropod mollusc Clione limacina is a predator, feeding on another pteropod mollusc, Limacina helicina. Essential elements of Clione's h unting and feeding behaviour can be evoked pharmacologically. The sens ory input driven by the presence of Limacina is mimicked by physostigm ine (PhS), the acetylcholinesterase inhibitor. Injection of PhS into C lione brought it to the state of hunting excitation accompanied by a r eversal of the reaction to head stimulation. As a result, head stimula tion, instead of a defence reaction, evoked active hunting behaviour. The 'fictive hunting behaviour', that is activation of main motor syst ems participating in hunting behaviour, could be evoked in a preparati on of the isolated central nervous system (CNS) by PhS application. To some extent, activation of the motor systems was realized through ser otonergic mechanisms. GABAergic mechanisms also play an important role in the organization of Clione's feeding behaviour. GABA application t o the preparation of the isolated CNS resulted in activation of the fe eding rhythm generator and excitation of the motoneurons supplying the protractor tentacle muscles. The results show that in gastropod mollu scs complex behaviour involving different functional systems may be de scribed in terms of the activity of single identified neurons.