Repetitive-motion display: A new behaviour in a burrowing alpheid shrimp

Abstract

Alpheidae are a highly diverse group of carideans with various life histories. They are known to possess specialized body forms and appendages, form facultative and obligate symbiotic relationships, and even exhibit complex behaviors like eusociality. This study represents the first documented association between the alpehid shrimp Alpheus rapax Fabricius, 1798 and the gobiid fish Myersina macrostoma. An undocumented behavioral display was observed in eight A. rapax individuals. The display was only performed in newly molted individuals while within their respective burrows in the presence of light. The display consisted on the following repetition: shrimp shifted its entire body forwards, with the cephalothorax angled downwards with respect to the pleon and both chelipeds extended forwards and towards each other; body jerked rapidly backwards with pleon curled and walking pereiopods extended; cephalothorax angled upwards, while the chelipeds were spread apart and moved backwards; and continuous undulations of pleopods. The display was hypothesized to either contribute to physiological requirements post molting or as a dishonest signal. © 2012 The Crustacean Society. Published by Brill NV, Leiden.