(full paper is archived in the Miller Library)
Title: The clustering behavior of Acmaea digitalis
Student Author(s): Millard, Carol S.
Faculty Advisor(s): Abbott, Donald
Location: Final Papers Biology 175H
Date: June 1966
Abstract: Acmaea digitalis populations often cluster on intertidal rocks at low tide. Clustering occurs in areas which receive some shade and some protection from direct wave action. Animals disperse on a rising tide. Reclustering occurs during tidal ebb while rocks are still wet, and takes place both day and night. A cluster varying in size from 22 to 44 individuals occupied an average of 15 square inches (range 8-20 in^2) each day over a 32 day period. Daily shifts in cluster position occured; total cumulative area occupied by the cluster in 32 days was 77 square inches. Only 17 members of the original cluster remained after 32 days, while a total of 22 new members entered.
Notes: Published 1968, Veliger 11(Suppl): 45-51