Variation in Larval Size After Eyestalk Ablation in Larvae of the Snapping Shrimp Alpheus Heterochaelis

Abstract

The effect of eyestalk ablation at various times on size (overall body length, carapace length, and body width) of fourth instar (postlarval instar during normal development) Alpheus heterochaelis was studied. Animals which underwent bilateral eyestalk ablation earlier in larval life grew to a significantly larger overall size compared to unablated controls and larvae ablated later. This growth was manifested as lengthening of the abdomen and was not expressed in the cephalothorax. The relationship between total body length attained and time of ablation was greatest among larvae ablated during Stage II, with overall size decreasing as time of ablation increased chronologically. The increase in overall size seen among larvae ablated progressively earlier may be a result of loss of hormonal control over hydromineral regulation and/or controlled manufacture and release of crustacean hyperglycemic hormone (CHH) by the X-organ-sinus gland, but it may also simply reflect a redirection of metabolic resources.