CERICOLA, Vincent*; DANIEL, Peter; Hofstra University; Hofstra University: The Phylogeny of Antennular Grooming Behavior in Decapod Crustaceans

Crustaceans groom their olfactory organ, the antennules, by wiping it through a pair of mouthpart appendages. Among reptantian decapods, glutamate (Glu), a chemical found in prey, stimulated AGB in the 4 lobster species but not the one crab species tested thus far; other chemicals were less effective (Barbato et al., 1997, Biol. Bull. 193:107-15; Wrobelwska et al., 2002, Chem. Senses 27:769-78). The asymmetric setae found in the tuft region of the lateral flagella of the antennules are the sole source of chemosensory input driving AGB (Schmidt & Derby, 2005, 208:233-48). In this study we have recorded AGB responses (wipes/min) to 14 chemicals found in prey in an additional 6 decapods representing more diverse taxa: achelata, homarida, brachyura, anomura, and Palaemonetes pugio as an outgroup. We also investigated the relationship between chemosensory activation of AGB and the presence and position of asymmetric setae through SEM examination of antennules. Chemosensory activation of AGB was observed in the 3 species of achelates and homarids tested. However responses to Glu were not significant and a larger number of chemicals elicited AGB then in the previous studies. A weak but significant response to alanine was observed in the anomuran, while no responses to chemical stimuli were observed in the brachyuran. Asymmetric setae were observed in all reptantians but were aligned along the tuft region laterally in the achelates and homarids and medially in the brachyuran and anomuran. P. pugio did not respond to chemicals and lacked asymmetric setae. We hypothesize that chemosensory activation of AGB evolved in lobster reptantians and has disappeared in the 2 crab taxa. We further hypothesize that laterally positioned asymmetric setae are necessary for chemosensory activation of AGB.