Animal Diversity Web

Ge­o­graphic Range

Varanus ex­an­the­mati­cus, or the sa­van­nah mon­i­tor, is found through­out most of Africa south of the Sa­hara (Steel 1996). It is found in west and cen­tral parts of Africa and south­ward to­ward Zaire (Rogner 1997).

• Biogeographic Regions
• ethiopian
  • native

Habi­tat

Varanus ex­an­the­mati­cus oc­cu­pies a va­ri­ety of habi­tats in Africa. Its pre­ferred habi­tat is the sa­van­nah, but they have adapted to other habi­tats as well. The lizards have adapted to habi­tats such as rocky dessert type areas, open forests and wood­lands. They are not found in the rain­for­est or deserts (Steele 1996).

• Terrestrial Biomes
• savanna or grassland
• forest

Phys­i­cal De­scrip­tion

V. ex­an­the­mati­cus has five sub­species (Steele 1996). This is why the mea­sure­ments and de­scrip­tions vary in much of the lit­er­a­ture. Varanus ex­an­the­mati­cus is a thick, stock­ily pro­por­tioned mon­i­tor. It has wide head, short neck and tail. The tail ta­pers and has a dou­ble toothed crest. Sa­van­nah mon­i­tors can reach lengths of up to 1.5 me­ters (Steele 1997). Other sources say they can reach sizes of up to 2 me­ters (Rogner 1997). Small sub-equal scales cover the cra­nial re­gion of the an­i­mal. The ab­dom­i­nal scale rows num­ber be­tween 60 and 110. The cau­dal scales of V. ex­an­the­mati­cus are keeled.

Varanus ex­an­the­mati­cus is gray to brown in color. There are rows of cir­cu­lar, dark edged yel­low spots across the an­i­mal's back. The tail has al­ter­nat­ing brown and yel­low­ish rings. The under body and in­side of the limbs is a yel­low­ish color. The tongue of V. ex­an­the­mati­cus is snake-like and blue in color (Steele 1996). (Rogner, 1997; Steele, 1996)

• Other Physical Features
• heterothermic

• Range mass

  1 to 70 kg

  2.20 to 154.19 lb

Re­pro­duc­tion

The breed­ing sea­son for V. ex­an­the­mati­cus is the same as the feast­ing pe­riod. They feast and breed dur­ing the wet sea­son (Steele 1996). When a male finds a mate he will fol­low her around re­lent­lessly, oc­ca­sion­ally bit­ing her on the neck and scratch­ing her neck and legs with his claws. Even­tu­ally the fe­male al­lows the two to mate.

The fe­male will dig a nest her­self and lay 20 to 50 eggs (Rogner 1997). Other sources say that the fe­male digs nests that are 15-30 cm deep and only lays up to 15 eggs (Ben­nett 1999). Some fe­males will lay their eggs in ter­mite mounds. The eggs of V. ex­an­the­mati­cus have an un­usu­ally high hatch rate of 100 % (Ben­nett). In­cu­ba­tion of the eggs takes five to six months and the eggs hatch out in March (Rogner 1997). In the sandy farm­lands of Ghana it has been re­ported that up to 55 ba­bies can be found in an area of 150,000m2 dur­ing Au­gust and Sep­tem­ber. The ju­ve­niles grow the quick­est dur­ing their first two months (Ben­nett 1999).

Lifes­pan/Longevity

• Average lifespan
  Status: captivity

  12.7 years

  AnAge

Be­hav­ior

Male V. ex­an­the­mati­cus are very ter­ri­to­r­ial and will de­fend their ter­ri­tory very ag­gres­sively. If two males come across each other they will try to in­tim­i­date each other by mak­ing threats. If this does not work, they will wres­tle and their bod­ies will be­come in­ter­twined as they bite each other. They can in­flict se­vere in­juries upon one an­other (Rogner 1997). When cor­nered, V. ex­an­the­mati­cus can be very ag­gres­sive. It will hiss loudly, thrash its tail and get ready to strike. If all this does not scare off a preda­tor, some have been known to play dead (Steele 1996).

Sa­van­nah mon­i­tors are most ac­tive dur­ing the day. They often seek shel­ter in bur­rows dur­ing the hot­ter parts of the day. Varanus ex­an­the­mati­cus use their tongue to sense their en­vi­ron­ment when they are out dur­ing the day. They flick their tongue an av­er­age of 20 to 40 every two min­utes. After they have at­tacked and bit­ten prey the tongue flick­ing rises to as many as 160 flicks every two min­utes. This helps the an­i­mal to find the in­jured and es­cap­ing prey (Steele 1996).

Food Habits

In the wild the diet of adult V. ex­an­the­mati­cus con­sists of small mam­mals, birds, snakes, toads, lizards, and eggs (Steele 1996). Other source con­tra­dict this find­ing and say that there is no proof that V. ex­an­the­mati­cus eat any type of ver­te­brate (Ben­nett 1999). Many adults also con­sume large quan­ti­ties of snails. Full grown V. ex­an­the­mati­cus have teeth that are quite blunt to help them crack and eat snails. The jaw has evolved to put max­i­mum lever­age at the back of the jaw to crush snail shells (Steele 1996). Adults will also eat car­rion if they come across it. Ju­ve­nile V. ex­an­the­mati­cus are mainly in­sec­ti­vores be­cause they lack the teeth to eat snails. Sa­van­nah mon­i­tors have evolved a way to eat poi­so­nous mil­li­pedes. The lizard will rub its chin on the mil­li­pede for up to fif­teen min­utes be­fore eat­ing it. It is be­lieved to do this to some how avoid the dis­taste­ful fluid that the mil­li­pede ex­cretes in it's de­fense (Steele 1996).

Varanus ex­an­the­mati­cus feed­ing habits re­volve around the weather. They use a feast and fast sys­tem. They feast dur­ing the wet sea­son when food is plen­ti­ful and easy to find. Dur­ing the dry sea­son they live off the fat re­serves they built up over the wet sea­son. The wet sea­son last for about eight months. Dur­ing this time V. ex­an­the­mati­cus can con­sume up to one tenth of its own body weight in a sin­gle day (Steele 1996).

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Varanus ex­an­the­mati­cus is very com­mon in the United States in pet store. It is also used in many lizard skin leather prod­ucts.

Con­ser­va­tion Sta­tus

Varanus ex­an­the­mati­cus is listed as a threat­ened species (Qual­ity De­sign 1998). In Africa it is per­se­cuted for its skin and as a source of food by the na­tives. The an­i­mal is also ex­ported in great num­bers for the pet trade.

• IUCN Red List

  Least Concern
  More information

• US Federal List

  Threatened

Con­trib­u­tors

Doug Diemer (au­thor), Michi­gan State Uni­ver­sity, James Hard­ing (ed­i­tor), Michi­gan State Uni­ver­sity.

Ref­er­ences

Ben­nett, D. "Uni­ver­sity of Ab­erdeen" (On-line). Ac­cessed Oct. 26, 99 at http://​www.​abdn.​ac.​uk/​~nhi770/monitors.​html.

Qual­ity De­sign, .. 1998. Ac­cessed Oct.25,99 at http://​www.​pclink.​com/​dkelly/​monitors.​htm.

Rogner, M. 1997. Lizards vol-2. Mal­abar Fl: Krieger pub­lish­ing.

Steele, R. 1996. Liv­ing Drag­ons. Lon­don: Ralph Cur­tis books.