Primary tabs

The hierarchical role of various sensory modalities in crayfish contests

Project Abstract: 
Animals must gather information from a fluctuating environment to reduce uncertainty and make decisions directly tied to survival and reproduction. For species that engage in agonistic contests over resources, information gained during contests can be used to make decisions about costly behaviors such as contest persistence and potential escalation. Signals can play an important role in modulating contest dynamics as well as playing a direct role in the outcome of a contest (i.e. retreating behavior). For example, gathering information about an opponent’s asymmetries compared to oneself (i.e. size, body condition, aggressiveness) may reduce costly behavioral errors. While understanding the role of a signal in these behaviors is important, input from multiple sensory modalities must be considered to realistically ascertain the complexity of these behavioral decisions. Crayfish are one of several decapod crustacean species that have been established as models for the role that chemical signals play in agonistic behavior contests. However, while we know that chemicals play an integral role in contest assessment and that chemical signals tend to play a larger role than other modalities (i.e. visual or tactile signals), we do not know the compounding role of all these signals. In other words, we do not know the intricacies of the information hierarchy that crayfish use during contest behavior. This study aims to tease apart that hierarchy and elucidate the context specific usage of three sensory modalities and their role in decision making during contest behavior.
Investigator(s): 
Years Active: 
2015
Methods: 
The purpose of this project is to determine potential differences in the reliance on a chemical signal (compared to visual or tactile information) under different contexts. Dyadic contests will be staged based on a 3 x 2 design. I will utilize three sensory block treatments (visual block, chemical block, tactile block) for different size treatments (size matched or size different) for male intrasexual contests. Prior to the contest, individuals will be injected with fluorescent dye (fluorescein) in order to visualize urine release. Black lights will be used to assist with the visualization of the fluorescent dye/urine solution released during the contest. For each contest, frequency and duration of urine release will be measured and each release time point will be paired with a behavior determined by an ethogram (Bergman & Moore, 2003). All animals used will be crayfish (Orconectes rusticus) collected from Maple Bay (Burt Lake). Due to the injection of foreign material and housing conditions that differ from natural conditions, all animals will be frozen at the conclusion of this project. Animals will be housed in flow-through troughs at the Lakeside Lab Research Facility and will be placed in individual containers within the troughs in order to eliminate social interactions prior to contests. All experiments will take place within the Lakeside Lab Research Facility as a completely darkened room will be necessary for urine visualization during contests.