EFFECTS OF EYESTALK ABLATION ON LARVAL MOLTING RATES AND MORPHOLOGICAL DEVELOPMENT OF THE AMERICAN LOBSTER,HOMARUS AMERICANUS

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Abstract
Larvae of the lobster, Homarus americanus, displayed abbreviation of subsequent molt intervals in response to bilateral eyestalk ablation at the 2nd stage. The interval in which the ablation occurred (2nd stage) was occasionally shortened. However, the 3rd stage molt interval was always abbreviated. At the 4th stage the ablated larvae were larger than intact controls. Removal of the last pair of swimming legs, as a control for the trauma of eyestalk ablation, slightly decreased growth but had no effect on molt interval lengths. Eyestalk removal sometimes resulted in 4th stage larvae with characteristics intermediate between normal 3rd and 4th stages. Eyestalkless larvae that were reared communally and fed frozen Artemia formed significant numbers of these intermediates. Eyestalkeless larvae reared individually and fed live Artemia nauplii rarely formed intermediates. These results imply that although eyestalks may be involved in the regulation of both the timing and growth increment of larval molting, they may not mediate the morphological aspects of lobster metamorphosis.