Publication Date


Document Type


First Advisor

Zar, Jerrold H., 1941-||Brower, James E.||Mathers, Carrol K.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Clams; Lampsilis siliquoidea


The activity (i.e. shell openings and closings) of the freshwater clam Larinsilis siliquoidea (Barnes) was continuously recorded for seven days in a L12:D12 light regime (i.e. 12 hr light alternated with 12 hr dark) followed by six days in constant darkness to determine if a rhythmical component was present. This procedure was repeated at 21, 12 and 6° C to evaluate the effect of temperature on activity. Shell openings were found to be of longer duration than closings at all temperatures in both L12:D12 and L0:D24. But no difference in duration between successive openings was observed between the two photoperiods at any temperature. The duration of openings and closings was found to increase with a decrease in temperature, and is probably related to a general slowing of physiological processes. A trend was indicated that shell closings were more frequent during the light portion of the photoperiod and shell openings were more frequent during the dark portion. This relationship continued in constant darkness, and may indicate the presence of an effective timing mechanism. A new monitoring technique utilizing a micropotentiometer was employed in this study, which allowed the specimens free movement in a simulated substrate. When compared to activity recorded from clams which were immobilized, a difference in activity patterns was noted. It is felt this monitoring technique is superior to those used in previous studies, as it allows for a more natural expression of the animal's behavior.


Includes bibliographical references.||Includes illustrations.


x, 26 pages, 21 unnumbered pages




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