Reinsel, K.A.*; Rittschof, D.; Foran, E.; Forward, Jr., R.B.: Larval release behaviors of decapod crustaceans: similar responses in shrimp and crabs

Ovigerous brachyuran crustaceans respond to peptide pheromones from developing embryos with stereotyped larval release behavior. This behavior involves rhythmic motion of the pleopods (pumping), which ventilates the egg mass and facilitates hatching of the embryos. We conducted behavioral studies using two European shrimp species, Paleomon serratus and Crangon vulgaris, and the North American grass shrimp Palaemonetes vulgaris to determine whether shrimp responses parallel published observations of brachyuran crabs. Focal stimulation of pleopods with crushed embryo extracts evoked pumping behavior in all 3 shrimp species. The rate of pumping in response to the stimulus increased with increasing embryo concentration. Bradykinin, a larval release peptide mimic, also evoked increased pumping responses in P. serratus and C. vulgaris. These results are consistent with observations of brachyuran crabs. In P. serratus, focal stimulation of aestetasc hairs evoked flicking of the antennules, whereas stimulation of the first walking legs evoked feeding responses; neither stimulated pumping. These results indicate that the receptors that mediate pumping behavior in shrimp are located on the pleopods.