Before entering fully into the the term bivalves, it is necessary to know its etymological origin. In this case, we can underline that it is a word of Latin origin that is the result of the sum of two components of that language:
-The prefix “bi-”, which can be translated as “two”.
-The noun “valve”, which is a term used to refer both to the turning of something and to the swing of a door and even to a part of the shell of a dried fruit.

The adjective bivalve is used to describe the being that has two valves. These valves, on the other hand, are the elements of great hardness that form the shell that certain invertebrate animals have or the parts that make up the shells of the fruits.

According to DigoPaul, the bivalves, in this way, are the animals of the class Bivalvia, belonging to the phylum of mollusks. There are about 13,000 species of bivalves, which have a shell that has two valves. The leaflets, which are lateral and generally symmetrical, are linked by conchiolin ligaments and a hinge.

Thanks to the presence of adductor muscles, the bivalves can open and close the leaflets. These animals can bury themselves on soft surfaces or inhabit hard surfaces. There are even species that have the ability to drill on solid ground.

Bivalves are aquatic (mostly marine). They can be very small animals, with shells of a couple of millimeters, or species weighing more than two hundred kilograms and large shells. Shells vary not only in size, but also in color and shape.

The feeding of the bivalves that live under the sand occurs through the filtration of water, extracting food from it. Bivalves do not usually move very much, although they do have a muscle that acts as a foot.

Within the bivalves, what is called the mantle plays an essential role. This element is the one that is responsible, through the secretion of a material, of shaping the shell and proceeds to cover the animal in question.

In addition to all the above, we can establish the existence of four types of bivalves, such as the following:
– Heterodonts, which have the peculiarity that their two valves are equal in size. They are marine and among them the cockles and clams can be highlighted.
-The protobranchs, which inhabit deep waters.
-The paleoheterodonto bivalves, which are currently extinct. They had a row of teeth and valves of equal dimensions.
-Pteriomorphic bivalves, which are also marine animals. Of these, it can be noted that they have eyes, that their gills are relatively large or that they even have a foot but small in size. In this group we can indicate that mussels are framed, among many others.

The mussels, the clams and oysters are some of the most popular bivalve animals. The three species are consumed by humans as food: the heat of cooking makes the valves open and thus it is possible to eat the body of the animal.