The beam of the flashlight penetrates the darkness, illuminating a small section of the gravel plain south of the seasonal Swakop River. North of the river the lights of Swakopmund are blinking. Waves can be heard crashing in the west. This is a night without stars because the desert is enveloped by the fog that has rolled in from the Atlantic Ocean. Sean Braine suddenly discovers a tiny glow in the beam of his flashlight. He moves towards it with determination, followed by his guests who have no idea what they are looking for.
A barking gecko (Ptenopus carpi) lies motionless, tightly pressed to the stony ground and well camouflaged in the light. These small reptiles are endemic to the gravel plains of the central and northern Namib Desert. Next, a spider of about eight centimetres “dances” in the flashlight. Then it pauses, stands on six of its eight long legs, the front legs and the abdomen raised. At the slightest movement the spider swings around, hence its name, the “Dancing White Lady” (Leuchorchestris arenicola). Researchers are still debating whether there might be two species: one that occurs on the gravel plains and another one in the dunes.
During the day the spider retreats into a burrow in the ground. The hiding place is about 40 cm deep and closed with a lid of fine cobwebs which has tiny bits of stone from the surroundings woven into it. In its well-camouflaged burrow the spider is also protected from the heat of the day. At night, however, it moves about in the vicinity of its hiding place in search of prey. It has two large pincers and kills its prey with poison, but it is harmless to humans. Sean’s expert eye detects the spider because of the glow in its big eyes. The Dancing White Lady has a total of eight big and small eyes.
Surprisingly we find a Namib sand gecko (Pachydactylus rangei), also called web-footed gecko, on the gravel plain. Sean explains that these nocturnal geckos usually occur in the dunes, and only sometimes on the plains near obstacles like bushes where dune sand has accumulated. In the ultraviolet light the skeleton of the gecko can be seen through the thin, colourfully patterned, yet almost transparent skin. This gecko has webbed feet so that it does not sink into the soft dune sand and is better able to dig.
The ultraviolet rays from black light make some scorpions visible, which are out hunting at night. They are hard to spot on the ground in the beam of the flashlight, but the fluorescent layer of hyaline in their exoskeleton makes them clearly visible in black light. On some of the night walks only scorpions of the species Uroplectus planimanus are discovered in various sizes (20-50 mm), while at other times species such as the black hairy thick-tailed scorpion (Parabuthus villosus) are also out and about.
At first glance the gravel plains of the Namib Desert seem deserted and empty. However, countless plants, lichens and animals have adapted to the harsh conditions in the oldest desert on earth. It is amazing how many creatures are out on the gravel plains under cover of darkness. The Braine family unveils these secrets to interested visitors on a two-hour night walk.
Author: Dirk Heinrich