Date of Award


Degree Type

Bachelors Essay

Degree Name

Bachelor of Science (BS)


Biological Sciences

First Advisor

Paul L. Carroll


The oyster is important for at least three reasons. First, it is important to the zoologist; second, it is a food which has developed million dollar enterprises; and third, the oyster is a domestic resource for the pearl and its allied industries. The oyster is a bivalve Mollusk, having symmetry in the larval stage but losing it in the adult stage. It has one large adductor muscle, somewhat posterior from the ligament which holds both valves together. The left valve forms a deeper pit than the right one as it is in the left valve that the oyster lies. It is interesting to note that the left valve is a good deal thicker than the right valve. Brooks (1905) simply states, "···· the left shell soon grows deep and spoon shaped, while the right one becomes a flat movable lid." It is on the heaviness of the valves that the oyster depends for its protection from its enemies because it leads a sedentary life, often fastening itself to rooks and other exposed objects. The animal is completely covered by two thin sheets of tissue which are called the mantle or pallium. Beneath the mantle are extensive gills running along most of the ventral side. In place of the foot which is typical of the Class Pelecypoda, the oyster has a visceral mass, having lost the foot early in the adult stage although it had one during the larval period. The oyster reproduces only sexually. It is either bisexual or unisexual, depending upon the species. Ostrea Virginica is unisexual. It has a well developed digestive, excretory, and respiratory system. The circulatory system is open, consisting of a ventricle, one auricle, and many blood vessels or lacunae.


A Thesis submitted to the Faculty of the College of Liberal Arts of Marquette University in Partial Fulfillment of the Requirements for the Degree of Bachelor of Science

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Biology Commons