Scallops

Scallops consist of two fan-shaped valves, which have concentric growth rings and radiating grooves. The valves are held together by a hinge on their flat side, and on this side there are projecting wings from the center, where the umbo lies. The valves are opened and closed by one large adductor muscle located in the middle of the scallop. This adductor muscle is so developed because the scallop is an active swimmer and it uses this muscle to snap its shell open and closed in order to propel itself through the water. On the inside of each of these valves are a row of blue eyes and sensory tentacles.

[The interior of the scallop is structured as seen in the diagram to the left.]

Oysters

Oysters also consist of two valves, but theirs are more rough and irregular, the lower shell is concave and contains the oysters soft body, while the top is more flat. Oysters attach themselves to one surface for life with the use of a limy secretion. Oysters open and close by using two adductor muscles on in the front (anterior) and one in the back (posterior).

[The interior of the oyster is structured as seen in the diagram to the left.]