Field guide training: Reptiles – Part 4

151 snake species are currently known in South Africa. 37 of these are poisonous and can be dangerous for humans, which is why you should learn more about these species when you train to become a field guide.

The main characteristic of snakes is their long, slender and legless body. Upper and lower jaw are not connected and only attached to each other by an elastic string of muscles. This characteristic enables the snake to dislocate their jaw and swallow prey, which is much larger and heavier than the snake itself. The teeth of the snake have the primary purpose to inject poison and digestive secretions into the prey’s body and are not functioning to chew on meat. The snake swallows its prey in one piece and the digestion takes place in the enterotomy.

Snakes have a forked tongue which is functioning as a highly sensitive olfactory organ. The tongue is able to sense the finest volatile substances in the air and can also feel the temperature. Hearing and eye vison of snakes is very little developed which is why they locate their prey though the body temperature of the other animal (mostly animals with a constant body temperature like birds or mammals). Another characteristic of snakes is that they molt, like other reptiles as well, three to four times a year, because their skin does not grow with their body.

Due to their poikilotherm lifestyle, snakes are dependent upon the temperature of their surroundings. If snakes live in regions with high variations in temperature over the year, they hibernate during the cold months. Their activity level will be reduced, and their fat resources are used as a source for energy.

During the summer months snakes reproduce and the males use pheromones to attract the females. 4 to 8 weeks after the fertilization the female lays the eggs in a safe area (e.g. dead stub of a tree or leaves). Depending on the species, a snake can lay 4 to 60 eggs. The eggs are hatched only through the temperature and moisture which surrounds them. After 2 to 3 months the young snakes will free themselves from the egg with the help of a specialized tooth, the egg tooth which the snake will lose while growing up.

Some snake species are viviparous, like the gaboon viper. Except for the python, snakes do not show parental behaviour which means that the young snakes are on their own after they are freshly hatched.

When you are working as a wildlife guide you should know about the toxic effect of the different snake species. The following list shows the important types of poisons and snake species which produce them:

• Haemotoxin (Boomslang): This type of poison hinders the blood coagulation which can lead to the exsanguination of the victim. The snakes have rutted fangs.

• Cytotoxin (Viper): It destroys the cell tissue around the wound. The fangs of snakes who are equipped with this type of poison are hollow and often foldout.

• Neurotoxin (Mamba, cobra): Paralysis and cramps are caused by this poison. In a worst-case scenario, it can lead to apnea. The fangs of these snake species are hollow and stiff.

If a snake bit you or another person, medical advice should be looked for immediately. In severe cases an antivenin is needed.