Internal Anatomy: Observation and Investigation
This activity uses:
For centuries people have been devising ways to get the "meat" out of the oyster. These techniques are referred to as "shucking."
If you would like to shuck your own oyster try the hinge method below, otherwise have your teacher shuck the oyster for you.
Orient the oyster so that the anterior end is pointed away from you. The dorsal and ventral sides of the oyster are determined by the internal anatomy. The dorsal side of the oyster is on your left, which is the location of the rectum and anus. The ventral side of the oyster is on your right, which is the location of the gills and mouth (Figure 4).
Take A Closer Look: Examine the surface of the oyster body. If you carefully shucked the oyster you may be able to see the small Quenstedt muscle. (Figure 5). This muscle is proposed to be a foot (pedal) remnant from the larval form of the oyster. It was named after a German geologist and paleontologist Friedrich August von Quenstedt.
The mantle is a thin layer of tissue that lines the inner part of each valve (Figure 6). It contains glands that extract elements from the water and convert them to compounds that make up each valve. Calcium carbonate makes up about 98 percent of each valve, this is the same material used to make chalk.
The adductor muscle (Figure 12) is composed of two types of fibers - translucent and white Ᾱ and is located toward the posterior end of the oyster below the visceral mass and pericardial cavity (Figure 13). The weight of this muscle accounts for 20-40 percent of the soft tissue weight of an oyster! You know about its strength if you have ever tried to open a live oyster.
The heart is located in the pericardial cavity that is covered by a thin tissue called the pericardium (Figure 14).
Next follow the pathway of the digestive system. An oyster's digestive system consists of labial palps, mouth, esophogus, stomach, digestive gland, intestine, rectum, and anus.
There are two labial palps, one associated with each gill. Each are bilobed, ciliated and function to sort and transfer food from the gills to the mouth.
Food is then passed from the mouth through a short esophogus to the stomach. The stomach is surrounded by the digestive gland that is the site for enzyme production and intracellular digestion.
From the stomach undigested and digested materials are passed to the intestines where absorption of nutrients and further processing of wastes occurs. Waste products are passed onto the rectum exiting out the anus.