(full paper is archived in the Miller Library)
Title: The lower limits of the habitats of Littorina scutulata and Littorina planaxis
Student Author(s): Peterson, Russell E.
Location: Final Papers Biology 175H
Date: June 1964
Abstract: Thus, the physical force of water and the biological force of predation combine to set a lower limit on the habitation of LIttorina. This limit facilitates their survival and functions through a mechanism of negative geotaxis. It is possible taht ling ago, the ancesotrs of these Littorina developed in two directions. One branch had a negative geotaxis and climbed out of the water. The other branch may have had a positive geotaxis or none. Those Littorina living below the water were eventually eaten by crabs, starfish, and fish while those aboe the sea have survived.