Mental scale

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The mental scale, or mental, in snakes and other scaled reptiles refers to the median plate on the tip of the lower jaw. [1] It is a triangular scale that corresponds to the rostral of the upper jaw. [2] The reference to the term 'mental' comes from the mental nerve which addresses the chin and lower jaw in animals. In snakes, the shape and size of this scale is sometimes one of the characteristics used to differentiate species from one another.

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In snakes and amphibians, the canthus, canthal ridge or canthus rostralis, is the angle between the flat crown of the head and the side of the head between the eye and the snout, or more specifically, between the supraocular scale and the rostral scale. It is defined as a sharp ridge in many viperids, but is rounded in most rattlesnakes, for example.

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Snake scale

Snakes, like other reptiles, have skin covered in scales. Snakes are entirely covered with scales or scutes of various shapes and sizes, known as snakeskin as a whole. A scale protects the body of the snake, aids it in locomotion, allows moisture to be retained within, alters the surface characteristics such as roughness to aid in camouflage, and in some cases even aids in prey capture. The simple or complex colouration patterns are a property of the underlying skin, but the folded nature of scaled skin allows bright skin to be concealed between scales then revealed in order to startle predators.

The labial scales are the scales of snakes and other scaled reptiles that border the mouth opening. These do not include the median scales on the upper and lower jaws. The term labial originates from Labium, which refers to any lip-like structure. In snakes, there are two different types of labial scales: supralabials and sublabials. The numbers of these scales present, and sometimes the shapes and sizes, are some of many characteristics used to differentiate species from one another.

Nasal scale

In reptiles, the nasal scale refers to the scale that encloses the nostril.

Rostral scale

The rostral scale, or rostral, in snakes and other scaled reptiles is the median plate on the tip of the snout that borders the mouth opening. It corresponds to the mental scale in the lower jaw. The term pertains to the rostrum, or nose. In snakes, the shape and size of this scale is one of many characteristics used to differentiate species from one another.

In scaled reptiles, the ocular scales are those forming the margin of the eye. The name originates from the term oculus which is Latin for "eye" and, in the broadest sense, refers to a scale associated with the eye. The numbers of these scales present, and sometimes the shapes and sizes, are some of many characteristics used to differentiate species from one another.

In reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scale. The term labial originates from Labium, which refers to any lip-like structure. The numbers of these scales present, and sometimes the shapes and sizes, are some of many characteristics used to differentiate species from one another.

In reptiles, the sublabial scales, also called lower-labials or infralabials, are those scales that border the mouth opening along the lower jaw. They do not include the median scale. The term labial originates from labium, which refers to any lip-like structure. The numbers of these scales present, and sometimes the shapes and sizes, are some of many characteristics used to differentiate species from one another.

Internasal scales

In snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. They are usually paired and situated just behind the rostral.

In reptiles, the nasorostral is an enlarged and usually paired scale, just behind the rostral.

Anal scale

In snakes, the anal scale is the scale just in front of and covering the cloacal opening. This scale can be either single or paired. When paired, the division is oblique. The anal scale is preceded by the ventral scales and followed by the subcaudal scales.

In reptiles, occipital scales are enlarged plates that lie directly behind the parietal scales.

Atractaspis aterrima, commonly known as the slender burrowing asp or mole viper, is a species of fossorial, venomous snake in the family Atractaspididae. The specific epithet, aterrima, meaning "blackest", is the superlative form of the Latin adjective ater, meaning "black".

References

  1. Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7th printing, 1985). 1105 pp. ISBN   0-8014-0463-0.
  2. Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. ISBN   0-89464-877-2.