In the world there are various species that have a special coating, which provides unique characteristics to those who possess it, said coating is called a scale, these are a species of fairly thin leaf, which is located in the dermis of certain species, in general, these are usually present in said organisms in large proportions and are superimposed between the skin. The primary function of these elements is to protect the specimen from damage, in addition to serving as a thermal insulator.

The scales can be classified according to the species in three main types, those belonging to fish, insects and reptiles. Those scales that cover insects, there are specific cases such as moths and butterflies where the scales are located in the region of the wings, their texture is similar to dust and for this reason they tend to come loose very easily, in these animals the scales are responsible for giving color to the insects. On the other hand, in the case of reptiles, they are structures that are made up mostly of keratin.

In the case of the scales that cover the fish, its main function is to provide protection to the fish from the different threats that exist in their natural habitat, in addition to providing other characteristics such as flexibility that allows a more effective swim. When talking about this type of scales, it is necessary that they be classified according to the type of fish that has them, since if it is cartilaginous fish, the scales tend to present small scales, these structures have a tip which points in rear direction, which allows the fish to have greater hydrodynamics, in particular cases such as sharks this structure is responsible for their surface being similar to that of sandpaper. Unlike cartilaginous fish, osteictia have three different types of scales, which can vary depending on their order or the family to which they belong, these can be highly variable in shape with respect to others, however their origin is tissue in all the cases.