Because formation of growth lines in the shells of bivalve molluscs is affected by environmental parameters, the growth lines should contain much information about the environments in which the animals live. However, the use of growth lines in ecology· and paleontology is limited by ambiguity in their identification.

Chione fluctifraga and Protothaca staminea were collected, marked, and replanted. C. fluctifraga were grown at three intertidal levels over a vertical range of one meter. In addition, P. staminea were grown at the middle level. All specimens were re-collected after 47 days. Acetate peels of shell cross sections were use for growth line counting.

Precision of counting was analyzed·by having six persons count lines on the same specimens. There was a significant difference between counters on number of lines per specimen, but excellent agreement in ranking of specimens by counts. This makes relative comparisons possible although absolute values may not be obtainable.

Younger (usually, smaller) specimens grew faster and formed more growth lines. Size was not always a good indicator of age. • This makes it important to use equivalent age classes for studies involving growth line count- There was an unexpected difference in growth rate between specimens grown at different intertidal heights. Those at the lower intertidal level grew less than those at the highest level. There was no difference between species in number of growth lines formed.

LLU Discipline





Graduate School

First Advisor

Conrad D. Clausen

Second Advisor

Jack W. Provonsha

Third Advisor

Elwood S. McCluskey

Fourth Advisor

Grenith J. Zimmerman

Fifth Advisor

Arthur V. Chadwick

Degree Name

Doctor of Philosophy (PhD)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Mollusks -- Growth.



Page Count

vi; 51

Digital Format


Digital Publisher

Loma Linda University Libraries

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This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives

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