THE CHELONIANS (shield reptiles)

The first fossil record dates back to the Early Triassic period, 210 million years ago.

In South Africa, we have 5 species of Turtles, 14 species of Tortoises and 6 species of Terrapins.

In France, we only use one word to speak about tortoises, turtles and terrapins. But what are really the differences between each of them?

Characteristics of cheloninans:

• 12 species of tortoises are endemic in South Africa.

• The shell consists of a domed dorsal (top) carapace and the flat ventral (bottom) plastron. It is made of bony plates which are the ribs and other bones fused together. In hatclings, the fusion is not yet complete and the shell of young is soft when squeezed. The plastron is concave in males (useful to mate) and flat in females.

• the scutes: bone bow is cvered by scutes, they grow as the tortoise get older. During warmer summer months, the scutes increase in size and stop growing in cooler winter months. These seasonal periods create rings, consisting of flat "valleys" in the growth periods and ridges during hibernation. To establish the age of a tortoise, we have to count the growth valleys between the ridges on the scute.

• Mouth and senses: they have no teeth. Instead they have a beak or a smooth cutting edge on the bottom jaw, composed of horn-like material. They have eyelids, external ears covered by the tympanic membrane. They have a poor hearing but a good sense of smell, a good vision and are able to distinguish certain colours.

• The bursa: the water is stored in an anal sac (bursa). This water is used to soften soil for eggs laying or reabsorbed for bodily functions. Just do not pick up tortoises during dry season because they stress, then urinate, so dehydrate and then have not much water available useful at this time.

• Incubation: In many species, the gender of hatcling is determined by egg incubation temperature: the females at higher temperature (31-34°C) and males at lower temperature (26-30°C). Eggs incubation temperatures are opposite in crocodiles!

• Chelonians are ectothermic; are active at temperature of 25-30°C and they go in hibernation at around 19°C.

• the smallest tortoise in South Africa is the speckled padloper.

speckled padloper

• the largest is the Leopard tortoise.
• the only one that can swim is the Leopard tortoise.

Leopard tortoise