It is necessary to view our lizards in the context of all the species of reptiles that inhabit the world.
Ornate Sandveld Lizard
The world's 6550 species of reptiles are divided into four orders - CROCODYLIA
- (crocodiles and alligators) - CHELONII
- (tortoises, terrapins and turtles) - SQUAMATA
- (snakes, lizards and amphisbaenians) - and RHYNCHOCEPHALIA
These four orders are divided - through sub-orders - into 48 Families, which are again divided into 900 genera. Of the world's 6550 species, Southern Africa has around 400 Species recorded so far, which is nearly a third of all reptile species occurring in Africa.
For comparison, the USA has 273 Species and Europe and south-west Asia has 380 species in areas much larger than southern Africa. Climate has much to do with distribution. The order SQUAMATA
is by far the largest group of living reptiles with 6200 species - exceeding the world's mammal species - and is divided into three sub-orders.
The sub-order SERPENTES
(Snakes) - contains over 11 families - divided into 417genera with around 2500 species worldwide. Southern Africa has 130 species of snakes of which only 34 have fangs and venom glands. Many of these have venom that is less toxic than that of wasps and bees.
Only 14 species of snakes can be considered dangerous to humans. The sub-order AMPHBAENIA
(Worm Lizards) is divided into 4 families with 21 genera containing about 140 species worldwide. Two families occur in Africa with only the AMPHISBAENIDAE
reaching southern Africa. This is by far the largest family with 15 genera containing about 130 species of which four genera with 12 species (three endemic) occur in our area.
Lizards belong to the sub-order SAURIA
, which is the largest group of living reptiles. Worldwide there are over 16 families divided into 400 genera containing over 3700 Species. There are four 'infra-orders', all of which are represented in southern Africa in 7 Families.
These 7 Families are represented by the - Chameleons, Agamas, Geckos, Monitors, SKINKS
, Plated & Girdled Lizards, and the Old World lizards which include the Mountain, Sandveld, Bushveld, Sand and Desert Lizards. SKINKS
are our 'typical' lizards with 75 Genera and over 600 Species worldwide. This is the second most diverse group of lizards in southern Africa (exceeded only by the Geckos), with 11 Genera containing 59 Species - of which one Genus and 31 Species are endemic.
After all those statistics, (with thanks to Bill Branch and his 'Snakes and other Reptiles of Southern Africa') - and within the Family SCINCIDAE
, is found the Sub-Family LYGOSOMATIINAE
(the Advanced Skinks), under which we find the Genus of Typical Skinks - the MABUYA
Among the numerous other species, the most common diurnal lizards we are likely to encounter around rest huts, farm buildings and town houses, are the Striped Skink (Mabuya striata)
- with two light stripes down the back, and the Rainbow Skink (Mabuya quinquetaeniata)
- with three light stripes down the back and many with a bright blue tail.
The Striped Skink is probably the most commonly seen of the two and will become quite conditioned to houses if not killed by cats and dogs. Males and females have similar colours. The Blue-Tailed (Five-lined) or Rainbow Skink prefers more rural habitat.
The young of both sexes have brilliant, electric blue tails. The adult female retains the blue tail with black stripes along the top and sides, while the adult male loses the back stripes for small, white bodyspots and develops a reddish-brown (orange) tail. Other species of lizard have blue or reddish tails and heads which appear to be used in communication.
The bright tails are also presumed to be a focal point for predators and a distraction when they are easily shed and continue wriggling after an attack. Both species of skink grow to quite a large size (20-25 cm) and males will prey on smaller species. The electric blue tails of the immature Rainbow Skinks stimulate territorial tolerance by the adults - similar to that enjoyed by birds of prey in immature plumage.
Humans have 'pineal glands' in the brain area, from which endocrines are secreted. The green, vegetarian, Iguanas of tropical forest habitats have 'pineal eyes' on the top of their heads, with which they are presumed to be able to measure ultra-violet light. The organ is covered by a transparent layer of skin through which light can pass and this assists them to locate the best sources of light for basking and energy control. In many species the 'pineal organ' is vestigial and its function is unclear.
Known but little studied, are the 'pineal organs' on many reptiles and particularly lizards. The pineal eye on the immature and female rainbow skinks is most obvious, while it is harder to see on the adult males and on the striped skinks. It may be of benefit in the optimum 'sunning' of these species but they, and other reptiles, also react to a warm substrate without any visible light.
In lizards, the pineal organ is thought to control breeding behaviour - possibly by measuring temperature and day length. Readers may add some interesting information by making observations on pineal organs on any reptiles which offer close scrutiny.
The angle of the head while 'sunbathing' and the reaction of the creature to shadow may provide some clues. The pineal 'eye' can be observed on top of the head, just behind the line of the eyes between the 'parietal' scales, with the assistance of binoculars.There is still so much to learn about many of our wild species - so don't be blinkered by the books that contain only what is know to date.
There is a lot that you can still add to the knowledge of our wildlife. Bear in mind that our reptiles are particularly vulnerable are have little escape from veld fires, which are probably the greatest cause of their destruction. Most of them control more insects and rodents than the predation by birds and mammals. Adam blamed the Eve - Eve blamed the snake - and the snake didn't have a leg to stand on!
Of the world's 6550 species, Southern Africa has around 400 species recorded so far, which is nearly a third of all reptile species occurring in Africa. For comparison, the USA has 273 species and Europe and south-west Asia have 380 species in areas much larger than southern Africa. Climate has much to do with distribution.