Bivalves are animals that have two valves.
Bivalve is an adjective that is used to describe a being that has two valves . These valves, for their part, are the very hard elements that form the shell that certain invertebrate animals have or the parts that make up the shells of fruits.
Before entering fully into the definition of the term, it is necessary to know its etymological origin. In this case, we can emphasize that it is a word of Latin origin that is the result of the sum of two components:
- The prefix bi- , which can be translated as “two” .
- The noun valve , which is a term used to refer to something that rotates, to the swing of a door, and even to a part of the shell of a nut.
What are bivalves
Bivalves, thus, are 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 valves, which are lateral and generally symmetrical, are linked by conchioline ligaments and a hinge.
Thanks to the presence of adductor muscles, bivalves can open and close their valves. These animals can bury themselves in soft surfaces or live on hard surfaces. There are even species that have the ability to make a hole in solid ground.
Mussels, clams and oysters are bivalves that are part of the human diet.
Its characteristics
Bivalves are aquatic (mostly marine). They can be very small animals, with shells measuring 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 bivalves that live under the sand occurs through water filtration, extracting food from it. Bivalves do not usually move much, although they have a muscle that acts as a foot.
Within bivalves, what is called the mantle plays an essential role. This element is responsible, through the secretion of a material, for giving shape to the shell and proceeds to cover the animal in question.
Types of bivalves
In addition to all the above, we can establish the existence of four types of bivalves:
- Heterodonts , which have the peculiarity that their two valves are equal in size. They are marine and among them we can highlight cockles and clams.
- Protobranchs, which live in deep waters.
- Paleoheterodont 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 highlighted that they have eyes, their gills are relatively large and they even have a foot but of a small size. In this group we can indicate that mussels are included, among many others.
Mussels , clams , and oysters are some of the best-known bivalve animals. The three species are consumed by humans as food: the heat of cooking causes the valves to open and thus it is possible to eat the animal's body.