Laboratory studies have been very important in understanding the physiology of commercially important crustaceans although removing crabs from their natural habitat can remove the crab from natural biological cues such as photoperiod, tidal cycles, and habitat. By assaying for circulating ecdysteroids in hemolymph of Dungeness crab, we can better understand how artificial settings are affecting the physiology of these crustaceans, in turn how they determine the outcome of laboratory studies by monitoring these differences between environments. The main goal of this project will be to determine whether there is a clear and present difference in ecdysteroid concentration between Tanner crab that have been exposed to lunar cycles; meaning they have tidal, temperature, depth and photoperiod influences, compared to lab setting Tanner crab, which will not have these external influences acting upon them.