Meeting Abstract

36.5  Friday, Jan. 4  Wave Energetics in Fiddler Crabs: Variability in Signaling Investment DAVIS, M. J.*; SWANSON, B. O.; Gonzaga University; Gonzaga University mdavis6@zagmail.gonzaga.edu

Fiddler crabs are a group of small, intertidal crustaceans that exhibit a high degree of sexual dimorphism. Male fiddler crabs are characterized by strong body asymmetry, as the large major claw can constitute more than half of the organism’s body mass. Males within this genus both wave the major claw to attract a mate during courtship, and also fight with the major claw for control of mating burrows. Both of these functions are essential for male mating success. Fiddler crab species are highly variable in claw morphology and in the kinematics of waving. Here, we quantify energetic investment in waving across 14 species of fiddler crabs. Using field observations and video analysis of courtship, we calculated waving rates (waves/second), waving time budgets (percent time spent waving), and the energetic cost of a wave (Joules/wave). Additionally, morphological and mechanical measurements were made for each of these species. Wave energetics are highly variable across species. Work (J) per wave varies by two orders of magnitude. Wave rates ranged from 0.29 to 1.1 waves/second. All species studied waved frequently during courtship periods, with 28% to 77% of time spent waving. Combining these data sets, we estimate each species’ energetic commitment to waving. We then use these data to test hypotheses about the relationship between waving investment and morphology (e.g. body size, claw force), and reproductive behavior.