Orconectes virilis Body Size and Shelter Preference

Abstract

Environment preference in terms of light and dark was tested on Crayfish (Orconectes virilis) from Itasca Lake in north central Minnesota. Twelve crayfish were caught from the lake and noted to be either “large” or “small”. Crayfish were individually put into one of two identical enclosures for 5 min. Every 30 sec the location of the crayfish was noted. The enclosures were divided up into four quadrants varying in covered or open and black or white sides/bottoms. Data was analyzed with graphs and chi square tests. Overall, crayfish spent a significant amount of time in the darkest covered quadrant. A significant difference was also found between the frequency of time spent in each quadrant between small and large crayfish; small crayfish remained in the darkest covered quadrant more than large crayfish.