What Does scale Mean
In order to know the meaning of the term scale, it is necessary, first of all, to discover its etymological origin. In this case, we can underline that it is a word that derives from Latin, exactly from “squama”, which can be translated as “scab” or “scale”.
The term scale refers to an epidermal or dermal sheet that covers, either partially or totally, the body of various species of animals. The scales overlap each other to isolate and protect the body.
The fish are animals that have scales. In this case, the origin of these flattened sheets is dermal, arising in the mesoderm layer. The characteristics of fish scales vary both in structure and in shape and size.
The process of formation of the scales of these aquatic animals begins after the consolidation of the mesenchyme, a tissue of the embryo . Then the induction of morphogenesis (when the epidermal papilla is formed) takes place and finally the so-called late metamorphosis.
In fish we can find different types of scales. The scales cycloid (smooth edges) and scales ctenoid (toothed) cover the body of silverside, spiny eels and other animals . Ctenoid scales, meanwhile, are divided into true ctenoid , espinoides and crenate .
The flakes ganoid can be found in fish and sturgeon spatulas, for example. In sarcopterygii, cosmoid scales appear . Stingrays and sharks , meanwhile, have placoid scales .
Of the ganoid scales it can be emphasized that they appear in lungfish and that they have a layer called isopedin, in which there is another layer of spongy bone.
Of the so-called placoid scales we can highlight several characteristics such as that, in the same way, they are known as dermal denticles, which do not grow but are added to the body of the fish as it grows and that are composed of a dental pulp that has blood vessels.
On the other hand, reptiles also have scales, but of epidermal origin and formed by keratin . These scales contribute to the conservation of moisture in the body, promote camouflage, facilitate locomotion and act as a shield. In snakes , to cite one case, they minimize friction and therefore reduce energy loss in movement.
In the same way, we cannot forget that there are also scales in other animals such as birds. In this case they have them in what are their legs, specifically in the fingers and can even be found in what is the ankle.
Of course, it should not be overlooked that there are certain mammals that are determined to have scales. It is true that it is unusual for this to occur, but they do appear in animals of this type such as the muskrat kangaroo, which has them in the area of their legs, or pangolins, which have them on their body, which are keratin and that come to serve as protection.