The Function of a Heteromorph Antennule in a Spiny Lobster, Panulirus Argus
1. The effects of electrical and mechanical stimulation upon a ‘naturally occurring’ heteromorph appendage growing in place of one eyestalk in Panulirus argus were examined. The heteromorph resembled the outer flagellum of the antennule in form. 2. Heteromorph stimulation elicited both a generalized withdrawal response, and a specific depression of the third segment and flagellum of the ipsilateral antennule. Such a depression response was also elicited upon stimulation of the ipsilateral outer flagellum of the normal antennule and by no other input investigated. 3. The basic similarity of the two responses was confirmed by electromyography and by intracellular recordings from motor neurons and interneurons within the lobster brain. 4. It was concluded that at least one afferent fibre component from the heteromorph and normal flagellum terminated upon the same interneuron pools, while avoiding others, and that consequently these observations provide evidence for the formation of functional inter-neuronal connexions according to type specificity.