The question, “What is a clam?” is a natural one for many people. Just the mention of a clam brings to mind the image of a giant mussel squeezing its way into an oyster and making the whole thing grow. For most people, that image is a classic, and probably the earliest picture that comes to mind when they think of clam consumption. But is it really a clam or more accurately a mussel?
To begin with, both mussels and clams are crescent shells. They are also both born in the same manner – by being “born” in a female reproductive organ called the oyster. They can be born either partially or fully, just like a human being. Because of this, they can be classified as clams and oysters.
The shape of a mussel’s shell is very important. Like a round egg, they have a flat inner shell, which is known as the “spermbox,” while the pointed end is called the anull (or mantle) and is what they eat. The clam’s other shell is called the astrolabula and it has a series of bumps on it like the eye of a bumblebee. The external shell is referred to as the cauda equina and has a series of ridges along it that serve to anchor the body and hold it steady. As a result, a clam can survive for years even without a shell. They only need to have one “spermbox” to stay alive.
In order to eat, a mussel must push itself out of the oyster and into the open ocean. When it comes to the question of what is a clam, this is where the similarities end. Unlike an oyster, a clam’s shell does not have a “spermbox” and instead is forced into position by pressure from inside. This is because a mussel only has one hard shell to keep it in place and since it cannot break the outer shell with the strength of its head, it has to break through it using other ways.
When we are thinking about what is a clam an oyster, we should remember that they are actually bivalve mollusks, which are an open-water balled relative of the oyster. Because of their lack of a shell, they are generally considered to be in the same category as sharks and whales. Clams are omnivorous, which means that they eat both meat and plants; they are a bit more unusual than oysters, however, in that they do not actively seek out their food but merely allow their natural eating instincts to take over and do so. A clams digestive track is very different than that of an oyster, leading scientists to believe that they obtain their nourishment from the soil around them, as well as being capable of chewing through and digesting wood and other organic matter.
Since we now know what a clam is, we can more accurately answer the question “what is a clam an oyster?” The true answer to this question, however, will probably elude us unless we have a clam in our aquarium! We can determine that a clam’s shell is approximately three to four times as large as an oyster’s, and that the clam is capable of growing to lengths of over fifteen inches! Clams are generally slow-moving and tend to stay put until they are provoked; after this time, they will run frequently in circles.
Although we have established what clams are, we should also highlight what an oyster is. An oyster, unlike a clam, is purely a balegalorm: its shell is designed to generate a protective covering to make it harder for the outside to come in contact with the interior. Like a clam, an oyster will flake, but unlike the clams, a pearl will not. For that reason, it is more common to find an oyster in a mussel or other body of water rather than in any fresh water.
Knowing what a clam is, what it looks like, and what it is made of (not its face) gives us valuable information about the natural history of these creatures. If you’re ever unsure about a particular animal, it is important to check out pictures or videos of it online to gain a better understanding of what it looks like. We have learned a lot about clams since they first appeared on land millions of years ago, and the chances are that we will never have a second chance at understanding their behaviors again. So is a clam an oyster?