A snake hatches with a fixed number of scales and the number do not increase as the snake matures nor do they reduce in number over time. They periodically molt their scaly skins and acquire new ones, which permits them to replace old worn out skin, disposal of parasites and allow the snake to grow. Scales may change the shape while molting. Smaller scales around the mouth and sides of the body in snakes allow expansions which help them in consuming prey of much larger width than itself.
Snake scales are formed by keratin and are differentiated by the snake's epidermis. Each scale has an outer surface and an inner surface. The skin from the inner surface hinges back and forms a free area which overlaps the base of the next scale which emerges below this scale.
| Scales of Head |
| Rostral scale |
Nasorostral scale |
 |
 |
| Rostarl scale is the median plate on the tip of the snout that borders the mouth opening in scaled reptiles. It’s similar to the mental scale in the lower jaw. Shape and size of this scale can be used to differentiate snake species from one another. |
Nasorostral is an enlarged and usually paired scale found in reptiles, just behind the rostral and in front of the nasal scale |
| |
|
| Nasal scale |
Internasal scales |
 |
 |
| Nasal scale is the scale that encloses the nostril, in reptiles and it may or may not be divided. When it’s divided the anterior half is known as the prenasal and the posterior half is known as the postnasal. Above the nasal scale located are the Supranasal scales. |
Internasal scales are found on top of the head between the scales that surround the nostrils in snakes and are usually paired. Theses are situated just behind the rostral. |
| |
|
| Brille (ocular scale, eye cap or spectacle) |
Ocular scales |
 |
 |
Brille is a German word used for “glasses”. It is the layer of transparent, immovable disc-shaped skin or scale covering the eyes of some animals. These are found mainly in animals without eyelids for protection. Fusion of the upper and lower eyelids has evolved the brille.
These are very clear in snakes but cannot be distinguished easily. It becomes cloudy and is visible as a cover over the eye when the snake is ready to ecdysis. It molts, and the brille is also shed as part of its skin. All geckos except those in the subfamily Eublepharinae (eyelid geckos) possess brilles. |
Oculus is a Latin word used for “eye”. The ocular scales form the margin of the eye. Number of scales, shape and size of these scales can be used to differentiate species from one another.
To indicate the positions or locations of the individual scales, (circumorbital scales ) certain prefixes are used:
- Preocular scales- lie directly in front of and in contact with the eye.
- Postocular scales- lie directly behind and in contact with the eye.
- Supraocular scales- enlarged scales on the crown immediately above the eye.
- Subocular scales- lie directly below and in contact with the eye.
|
| |
|
| Loreal scales |
Interorbital scales (supraoculars) |
 |
|
| Loreal scale lie between the eye and the nostril of snakes which is analogous to the lore on birds which corresponds to the region between the eye and the beak. |
interorbital scales, are the scales on the top of the head between the plates surmounting the eyes, in snakes. |
| |
|
| Frontal scale |
Prefrontal scales |
 |
 |
Frontal scale lie in the general region of the forehead of a snake, more sprecifically between the eyes and to the anterior of this area which is analogous to the frontal bone on a human which corresponds to the forehead.
Prefrontals are snake scales attached to the frontals and to its anterior. |
Prefrontal scale is connected to the frontals towards the tip of the snout of the snake which are in contact with the interanasal. |
| |
|
| Parietal scales |
Occipital scales |
 |
 |
| Parietal scale is located on the snake head and connected to the frontals towards the posterior. These scales are analogous to and take their name from the parietal bone which forms the roof and sides of the cranium in humans. |
Occipital scales are enlarged plates that lie directly behind the parietal scales in reptiles. Interoccipital scale is located between the occipital scales |
| |
|
| Temporal scales |
Labial scales |
 |
 |
Temporal scales are found on the side of the head between the parietal scales and the supralabial scales, and behind the postocular scales.
There are two types of temporal scales:
- Anterior temporals- contact with the postocular scales.
- Posterior temporals (secondary and tertiary temporals) found in vertical rows not in contact with the postocular scales.
|
Labium is a Latin word for “lip” witch has given rise to the word labial . Labial scales border the mouth opening of reptiles but it does not include the median scales on the upper and lower jaws.
Number of scales, shape and size of these scales can be used to differentiate snake species from one another.
There are two different types of labial scales found in snakes.
- Supralabials- form part of the upper lip. Also called upper labials.
- Sublabials (infralabials or lower labials) - form part of the lower lip.
|
| |
|
| Supralabial scales (upper-labials) |
Sublabial scales (lower-labials or infralabials) |
 |
|
| Supralabial scales, border the mouth opening along the upper jaw in reptiles. It does not include the rostral scale. Number of scales, shape and size of these scales can be used to differentiate snake species from one another. |
Sublabial scales, border the mouth opening along the lower jaw. It does not include the mental scale. The numbers of these scales present, and sometimes the shapes and sizes, are some of many characteristics used to differentiate species from one another. |
| |
|
| Mental scale |
Chin shields |
 |
 |
| Mental scale is the median plate on the tip of the lower jaw of reptiles. It is a triangular scale and corresponds with the rostral of the upper jaw. Mental nerve gives rise to the word Mental which addresses the chin and lower jaw in animals. The shapes and the sizes are some of many characteristics used to differentiate species from one another. |
Chin shields are found on underside of the snake's head towards the anterior and touching the lower labial scales. Chin shields to the front of the snake, towards the snout are referred as anterior chin shields and those to the rear of the snake, towards the tail are referred as posterior chin shields. |
| |
|
| Gular scales |
|
 |
|
| Gular scales found on the underside of a snake's head, in the central or throat region. These are in contact with the first ventral scales of a snake's body and are flanked by the chin shields. |
|
| Scales on the body |
| Dorsal scales (Costal) |
Vertebral scales |
 |
 |
Dorsal scales are found as longitudinal series of plates that encircle the body of the snakes, but it does not include the ventral scales.
Counting of dorsal scales, numbers are often given for three points along the body corresponding to the number of dorsal scales around the body at a head's length behind the head, at midbody and at a head's length before the vent. One number refers to the midbody count.
Dorsal scales are counted diagonally, starting with the paraventral scale row. Some dorsal scale rows are raised, keeled or smooth as opposed to the others. |
Vertebral scales are large scales found in snakes along the top of the back (uppermost row). These are a specialised form of dorsal scales. Vertebral is a term associated with the backbone. It also associates with the central scales on the carapace of a chelonian shell. |
| |
|
| Ventral scales (gastrosteges) |
|
 |
|
| Ventral scales are enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale, which are found on snakes. When counting, first is the anterior most ventral scale that contacts the paraventral row of dorsal scales on either side, but the anal scale is not counted. |
|
