Meeting Abstract

3.3  Thursday, Jan. 3  Clawing your way to the top: variation, repeatability and social benefits of chela strength in slender crayfish ANGILLETTA, M. J.*; WILSON, R. S.; Indiana State Univ, Terre Haute; Univ of Queensland, St. Lucia mangilletta@indstate.edu

Animals commonly signal their strength to conspecifics during disputes over resources or mates. In crayfish, such threats involve the chela (or claw), which is capable inflicting considerable damage to an opponent. Surprisingly, chela size is a poor indicator of chela strength, commonly leading to situations where crayfish signal dishonestly. We found that the strength of crayfish was highly repeatable between days and between temperatures, indicating that dishonest signaling is a reliable phenomenon. We then asked whether male crayfish use information about their relative strength (i.e., the residual of chela strength regressed on chelae size) when interacting with other males. A simple optimality model was developed to predict whether a crayfish would run from an opponent of a given claw size. Our model made predictions under three scenarios: 1) crayfish use information about their own strength relative to their opponent�s expected strength, 2) crayfish use information about their own strength relative to their opponent� actual strength, and 3) crayfish use no information about strength. Staged encounters between focal individuals and random opponents provided support for the third scenario: crayfish seem unaware of their own relative strength and are unable to gauge the actual strength of their opponents. Dishonesty provides clear social benefits to slender crayfish, but the costs that maintain this unusual system of signaling remain unknown.