Difference between revisions of "Snake Skin"
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| − | + | ==Function and Morphology== | |
Reptile skin functions to protect from physical trauma, desiccation, infection, osmotic damage and extremes of temperature. There are several layers. The dermis is mainly connective tissue but contains the pigment cells. The epidermis is characterised by scales that are covered with keratin. The size and shape of scales varies greatly among [[:Category:Snake Species|species]], for example the [[Bushmaster|bushmaster]] has scales that are large with a dermal core or [[Osteoderm|osteoderm]] while they may be partially overlapping and keeled in the [[Rattlesnake|rattlesnake]]. The smallest scales are seen in the [[Boidae|boids]] and worm snakes. The ventral scales (or scutes) are generally larger and thicker than the lateral and dorsal scales. | Reptile skin functions to protect from physical trauma, desiccation, infection, osmotic damage and extremes of temperature. There are several layers. The dermis is mainly connective tissue but contains the pigment cells. The epidermis is characterised by scales that are covered with keratin. The size and shape of scales varies greatly among [[:Category:Snake Species|species]], for example the [[Bushmaster|bushmaster]] has scales that are large with a dermal core or [[Osteoderm|osteoderm]] while they may be partially overlapping and keeled in the [[Rattlesnake|rattlesnake]]. The smallest scales are seen in the [[Boidae|boids]] and worm snakes. The ventral scales (or scutes) are generally larger and thicker than the lateral and dorsal scales. | ||
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The skin is dry, with few glands compared with mammals and amphibians. | The skin is dry, with few glands compared with mammals and amphibians. | ||
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==Epidermis== | ==Epidermis== | ||
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The epidermis consists of 3 layers: | The epidermis consists of 3 layers: | ||
| − | * | + | * Stratum germinativum - which divides and produces keratin. |
| − | * | + | * Stratum intermedium - which contains lipid, thus preventing fluid loss. |
| − | * | + | * Stratum corneum - which forms scales and scutes. |
In reptiles, 2 forms of keratin are present: | In reptiles, 2 forms of keratin are present: | ||
| − | * | + | * Alpha-keratin which is flexible and often found between scales and scutes and in hinges. |
| − | * | + | * Beta-keratin which is unique to reptiles. It is harder than alpha-keratin and forms scutes and scales. |
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==Dermis== | ==Dermis== | ||
| − | The dermis of reptiles contains pigment cells, [[Snake Neurological System|nerves]] and vessels, although thick, keratinised skin is without cutaneous sensation, leaving captive reptiles at risk of [[Snake Vesicular Dermatitis| | + | The dermis of reptiles contains pigment cells, [[Snake Neurological System|nerves]] and vessels, although thick, keratinised skin is without cutaneous sensation, leaving captive reptiles at risk of thermal burns. |
| − | + | * Find out more about [[Snake Vesicular Dermatitis|snake vesicular dermatitis (blister disease)]]. | |
| − | + | ==Glands== | |
| + | Almost no skin glands occur in snakes, but [[Cloaca|coacal]] scent glands (anal glands) are present. They occur at the base of the tail, dorsal to the [[Hemipenes|hemipenes]] in a male, and open into the posterior margin of the cloaca. These organs play a role in defense resulting from their unpleasant odour, which may also carry socail signals. These may become enlarged, impacted, or abscessed in captivity. | ||
==Skin adaptations and cutaneous appendages== | ==Skin adaptations and cutaneous appendages== | ||
| − | *[[Snake Eye| | + | *[[Snake Eye|Spectacles]] - are clear scales over the eyes of snakes. |
| − | * | + | *[[Snake Special Senses|Heat sensory pits]] (infrared-sensitive receptors) - are deep grooves between the nares and the [[Snake Eye|eye]] of [[Pit viper|pit vipers]], [[Pythoninae|pythons]] and some [[Boidae|boas]] which allow them to 'see' the radiated heat of their prey. These pits can also be found on the upper lip, just below the nares, termed 'labial pits'. |
| − | * | + | *Rattle - present in some snakes and used to warn predators. It is enlarged with each [[Snake Shedding|shed]]. |
| − | * | + | *Gastropeges - are a single row of large ventral scales in snakes that aid [[Snake Locomotion|locomotion]]. |
| + | ==References== | ||
| + | Mader, D.R. (2005). Reptile Medicine and Surgery. Saunders. pp. 51 ISBN 072169327X | ||
[[Category:Snake_Anatomy]] | [[Category:Snake_Anatomy]] | ||
Revision as of 10:40, 28 April 2010
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Function and Morphology
Reptile skin functions to protect from physical trauma, desiccation, infection, osmotic damage and extremes of temperature. There are several layers. The dermis is mainly connective tissue but contains the pigment cells. The epidermis is characterised by scales that are covered with keratin. The size and shape of scales varies greatly among species, for example the bushmaster has scales that are large with a dermal core or osteoderm while they may be partially overlapping and keeled in the rattlesnake. The smallest scales are seen in the boids and worm snakes. The ventral scales (or scutes) are generally larger and thicker than the lateral and dorsal scales.
The skin of reptiles has numerous functions including display, protection, camouflage, thermoregulation and fluid homeostasis.
The skin is dry, with few glands compared with mammals and amphibians.
Epidermis
The epidermis consists of 3 layers:
- Stratum germinativum - which divides and produces keratin.
- Stratum intermedium - which contains lipid, thus preventing fluid loss.
- Stratum corneum - which forms scales and scutes.
In reptiles, 2 forms of keratin are present:
- Alpha-keratin which is flexible and often found between scales and scutes and in hinges.
- Beta-keratin which is unique to reptiles. It is harder than alpha-keratin and forms scutes and scales.
Dermis
The dermis of reptiles contains pigment cells, nerves and vessels, although thick, keratinised skin is without cutaneous sensation, leaving captive reptiles at risk of thermal burns.
- Find out more about snake vesicular dermatitis (blister disease).
Glands
Almost no skin glands occur in snakes, but coacal scent glands (anal glands) are present. They occur at the base of the tail, dorsal to the hemipenes in a male, and open into the posterior margin of the cloaca. These organs play a role in defense resulting from their unpleasant odour, which may also carry socail signals. These may become enlarged, impacted, or abscessed in captivity.
Skin adaptations and cutaneous appendages
- Spectacles - are clear scales over the eyes of snakes.
- Heat sensory pits (infrared-sensitive receptors) - are deep grooves between the nares and the eye of pit vipers, pythons and some boas which allow them to 'see' the radiated heat of their prey. These pits can also be found on the upper lip, just below the nares, termed 'labial pits'.
- Rattle - present in some snakes and used to warn predators. It is enlarged with each shed.
- Gastropeges - are a single row of large ventral scales in snakes that aid locomotion.
References
Mader, D.R. (2005). Reptile Medicine and Surgery. Saunders. pp. 51 ISBN 072169327X