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Date of Award


Document Type


Degree Name

Master of Arts (M.A.)


Biological Sciences

First Advisor

Joel W. Hedgpeth

First Committee Member

Ernest P. Edwards

Second Committee Member

John S. Tucker


Interest in the endemic Pisaster was first aroused by the great variation of external color in Pisaster ochraceus. This in turn led to observations of the diversity of the spinous patterns of this sea star. Following the suggestion of Dr. Jool D. hedgepeth it was decided to make an extensive comparison of the common species of Pisaster.

Detailed comparison between Pisaster brevispinus and Pisaster ochraceus have been made only by Fisher (1930) and Verrill (1914). Both of these investigators restricted their observations largely to the endoskeleton and its calcareous protuberances. In addition to analyzing the work of Fisher, an attempt to differentiate between the two species regarding behaviour, tolerances, gross anatomy and natural history has been made. In addition some mention of the relationships with other members of the family Asteriidae is recorded in this study.



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