Changes

{{unfinished}}

{{review}}

[[Image:BlueTonguedLizard.jpg|200px|thumb|right|'''Blue-tongued Skink''' (Wikimedia Commons)]]

[[Image:BlueTonguedLizard.jpg|300px|thumb|right|'''Blue-tongued Skink''' (Photo credit: Sean Mack, Wikimedia Commons)]]

[[Image:Monitor_tongue.jpg|100px|thumb|right|'''Forked tongue in a monitor''' (Wikimedia Commons)]]

 

==Mouth==

==Mouth==

Lizard teeth are used for grasping, piercing and breaking food or, in the case of [[Monitor|monitors]], slicing and cutting. Mollusk-eating Caiman lizards (''Dracaena guianensis'') and adult [[Monitor|Nile monitors]] (''Varanus niloticus'') have broad rounded cheek teeth for crushing shells.

Lizard teeth are used for grasping, piercing and breaking food or, in the case of [[Monitor|monitors]], slicing and cutting. Mollusk-eating Caiman lizards (''Dracaena guianensis'') and adult [[Monitor|Nile monitors]] (''Varanus niloticus'') have broad rounded cheek teeth for crushing shells.

The teeth are generally '''pleurodont''' (attached to the sides of the mandible without sockets) but in some families, such as [[Water Dragon|agamids]] ([[Lizard Classification|Agamidae]]) and [[Chameleon|chameleons]] (Chamaeleonidae), they are '''acrodont''' (attached to the biting edges of the jaws without sockets). The teeth of the venomous [[Gila Monster|Gila monster]] and the [[Mexican Beaded Lizard|Mexican beaded lizard]] are grooved to allow the flow of venom; however they have no direct connection to the sublingual venom glands. Venom is injected with the chewing action as it flows along the dental grooves.

The teeth are generally [[Pleurodont dentition|pleurodont]] (attached to the sides of the mandible without sockets) but in some families, such as [[Water Dragon|agamids]] ([[Lizard Classification|Agamidae]]) and [[Chameleon|chameleons]] (Chamaeleonidae), they are [[Acrodont dentition|acrodont]] (attached to the biting edges of the jaws without sockets). The teeth of the venomous [[Gila Monster|Gila monster]] and the [[Mexican Beaded Lizard|Mexican beaded lizard]] are grooved to allow the flow of venom; however they have no direct connection to the sublingual venom glands. Venom is injected with the chewing action as it flows along the dental grooves.

Pleurodont teeth are shed and replaced whereas acrodont teeth are only replaced in very young specimens. For [[Water Dragon|agamids]] and [[Chameleon|chameleons]], special care should be taken to avoid damaging the acrodont teeth when opening a lizard's mouth with a rigid speculum as these teeth are irreplaceable. Furthermore, acrodont dentition is reportedly susceptible to [[Lizard Periodontal Disease|periodontal disease]].

[[Pleurodont dentition|Pleurodont]] teeth are shed and replaced whereas [[Acrodont dentition|acrodont]] teeth are only replaced in very young specimens. For [[Water Dragon|agamids]] and [[Chameleon|chameleons]], special care should be taken to avoid damaging the [[Acrodont dentition|acrodont]] teeth when opening a lizard's mouth with a rigid speculum as these teeth are irreplaceable. Furthermore, [[Acrodont dentition|acrodont]] dentition is reportedly susceptible to [[Lizard Periodontal Disease|periodontal disease]].

===Tongue===

===Tongue===

The organs and divisions of the gastrointestinal tract are similar to those of mammals. The lizard has a simple, J-shaped, elongated stomach. A caecum is present in many species. The large intestine is thin-walled and less muscular than the stomach or small intestines.

The organs and divisions of the gastrointestinal tract are similar to those of mammals. The lizard has a simple, J-shaped, elongated stomach. A caecum is present in many species. The large intestine is thin-walled and less muscular than the stomach or small intestines.

[[Lizard Feeding|Herbivorous]] lizards such as the [[Green Iguana|green iguana]], [[Prehensile-tailed Skink|prehensile-tailed skink]], [[Spiny-tailed Lizard|egyptian spiny-tailed lizard]] and [[Chuckwalla|chuckwalla]] (''Sauromalus obesus'') have a sacculated colon to facilitate hindgut fermentation. These animals usually have higher [[Preferred optimum temperature zone|optimal body temperature zones]] in order to enhance microbial fermentation.

[[Lizard Feeding|Herbivorous]] lizards such as the [[Green Iguana|green iguana]], [[Prehensile-tailed Skink|prehensile-tailed skink]], [[Spiny-tailed Lizard|egyptian spiny-tailed lizard]] and [[Chuckwalla|chuckwalla]] (''Sauromalus obesus'') have a sacculated colon to facilitate hindgut fermentation. These animals usually have higher [[Preferred optimum temperature zone|optimal body temperature zones]] in order to enhance microbial fermentation.

==Cloaca==

==Cloaca==

A cloaca is present (with a transverse cloacal slit) and is divided into three parts:

A [[Cloaca|cloaca]] is present (with a transverse cloacal slit) and is divided into three parts:

* coprodeum (collects faeces)

* coprodeum (collects faeces)

* ureodeum (collects urinary wastage)

* ureodeum (collects urinary wastage)

* proctodeum (final chamber prior to elimination)

* proctodeum (final chamber prior to elimination)

==References==

==References==