Symmetry It is a notion that comes from Latin symmetry, although this word has its origin in the Greek language. The term is used with reference to the correspondence which is registered in the position , he size and the shape of the parts That make up a whole. Bilateral , on the other hand, is that which is linked to the two parts or the two sides of something.
In the context of the biology , the symmetry mentions the ideal arrangement of the body and its parts with respect to a plane, a center or an axis. The concept of bilateral symmetry contemplates a single plane (the sagittal plane ), which causes body division into two halves which, in theory, are identical.
Bilateral symmetry, in this way, implies the division of the organism into a right half and one left half , separated by a axis . If you would take a frontal plane (perpendicular) instead of the sagittal plane, the body would be divided into one ventral half and one dorsal half .
In relation to the aforementioned symmetry in what is the human body we have to say that what is known as Vitruvian man takes a special role. It is a drawing made in the year 1490 by the genius Leonardo da Vinci, which clearly shows the same and also the set of proportions of the body of man.
Species that have bilateral symmetry are classified as bilateral . In sayings animals , the organism is symmetrical with respect to the sagittal plane. In these cases, the sides of the body are identical, although the lower half and the upper half have marked differences.
No less interesting is to know another series of data concerning living beings that do have bilateral symmetry, among which are:
-It is considered that a clear difference that identifies the animals that have the same is that they have organs and organ system.
-It is established that living beings that are characterized by having it are framed within what would be a higher level. And it is established that they have managed to have a more remarkable development of organs and tissues than those who do not.
- Specifically, the animals that have this type of symmetry are classified, as a rule, in three: the pseudocellomados, the celomados and the acelomados.
-It is interesting to know that there are certain animals that have the particularity that, although at first they do have the symmetry that occupies us, then, as they develop, it disappears instead. This would be the case, for example, of the starfish or the hedgehogs that start having it but then, as they grow and develop, it becomes a secondary-type pentarradial symmetry.
Importantly, bilateral symmetry contributes to the cephalization and to the development of a Central Nervous System . In this way, this symmetry is linked to the formation of a head which becomes the center of the mentioned nervous system.
It should be noted that many plant species also have bilateral symmetry, as is the case with orchid .