Further down the evolutionary scale, a variety of reptiles and amphibians thrive in Makgadikgadi's arid expanses, though most pass unseen by the visitor. Acacias, with their deeply fissured bark and abundance of insect prey, provide havens for skinks and geckos above the open grassland. At ground level, the ground agama ambushes termites from a hollow at the foot of a shady bush, while the legless Kalahari burrowing skink swims just below the surface of the sand in search of beetle larvae, and is often found drowned when pans fill up overnight. In sandier areas, barking geckos emerge from their burrows on summer evenings and fill the Kalahari night with their bizarre territorial clicking calls.

Perhaps the highlight of Makgadikgadi's smaller animals is one that few have either heard of or seen: the Makgadikgadi Spiny Agama (Agama makarikarica). This is a small species of the agama family – a lizard – that's endemic to Makgadikgadi. It feeds on termites and beetles, and lives in tunnels at the base of bushes.

The acacia woodland is home to a broad cross-section of typical bushveld reptiles, including monitor lizards (both water and rock), flapneck chameleons and leopard tortoises. Snakes encountered at ground level include black mamba, snouted cobra, African egg-eater, mole snake and the ubiquitous puff adder, while arboreal species such as boomslang and spotted bush snake hunt chameleons and birds' eggs among the thorny tangle.

To survive this harsh habitat, many frogs aestivate below ground during the dry season. Giant bullfrogs emerge from their mud cocoons after seasonal rains to take over temporary pans in a frenzy of breeding. These frogs are so aggressive that they have even been observed snapping at lions. The much smaller rain-frogs of the Breviceps genus, like the bushveld rain frog, Breviceps adspersus, have toughened feet, evolved for digging their burrows. They also appear with the rains, and gather at the surface during termite emergences, cramming in as many of the hapless insects as time will allow.

The Kalahari teems with invertebrate life. Good years bring swarms of locusts and mass migrations of butterflies to the grasslands, while countless termites demolish and carry away the dead vegetable matter that carpets the ground. Termites are fundamental to the ecology of the region. Not only do they recycle and enrich the soil, but they are also a vital prey species for everything from eagles and aardvarks to skinks and spiders.

There are 14 genera of termites, each of which has a different mode of foraging: harvester termites (Hototermitidae) nest in underground burrows, while Odontoterme termites construct the enormous raised mounds that can be seen for miles across the grasslands – each one a miracle of air conditioning.

Among a multitude of other insects are the wingless tenebrionid beetles, which scuttle rapidly across open ground on long legs and squirt a noxious fluid at attackers. More visible are the chunkier dung beetles, which swarm on strong wings to fresh animal dung, then roll it away and bury it as 'brood balls' in which their eggs are laid and their larvae mature.

On hot summer days, thickets throb with the stridulating calls of cicadas, the adults having only two weeks of life in which to mate and deposit their eggs, after up to 17 years underground larval development.

Termites and other insects feed a host of invertebrate predators. Sand divers (Ammoxennidae) are small, fast-moving spiders that paralyse termites with their venom and bury themselves if disturbed. Golden orbweb spiders (Nephiladae) string their super-strong webs between thorn bushes to ensnare flying insects.

Contrary to popular belief, sun-spiders, or solifuges (Solifugae), are not venomous, but pursue insects at high speed across the ground and despatch them audibly with powerful mandibles. You'll often see these large arachnids running across the ground at night near campfires. Though frightening at first, they're totally harmless and don't bite people!

Not so harmless are the resident scorpions, which detect the vibrations of prey through their body hairs. As a rough rule of thumb for the nervous, species with larger pincers and slimmer tails have less powerful venom than those with smaller pincers and larger tails.

Red velvet mites are parasites on larger invertebrates and often gather in sandy areas in the early morning after rain showers, looking like tiny scarlet cushions. Another tiny parasite, the voracious tampan tick, lurks in the sand beneath camelthorn trees and, chemically alerted by an exhalation of its victim's CO2, emerges to drain the blood from any unsuspecting mammal that fancies a nap in the shade.

High-rise living

The towers of mud built by termites, known as termitaria, are often the only points of elevation for miles across the Makgadikgadi grasslands. Not all termites build mounds – harvester termites (Hodotermitidae), which are common on Kalahari sands, leave little evidence of their underground tunnels above the surface – but those that do, the Macrotermitidae species, are responsible for one of the true wonders of nature.

Communicating entirely through pheromones, millions of blind worker termites can raise several tons of soil – particle by particle – into an enormous structure over three metres high. Below the mound lies the nest, where separate chambers house brood galleries, food stores, fungus combs (where termites cultivate a fungus that can break down plant cellulose for them) and the queen's royal cell. The queen produces up to 30,000 eggs a day, which means – since she lives for many years – that the millions of inhabitants of the colony are all brothers and sisters.

The whole structure is prevented from overheating by a miraculous air-conditioning system. Warm air rises from the nest chambers, up a central chimney, into thin-walled ventilation flues near the surface (you can feel the warmth by placing your hand just inside one of the upper vents). Here it is cooled and replenished with oxygen, before circulating back down through separate passages into cavities below the nest chambers. Finally, before returning to the nest, it passes through specially constructed cooling veins, kept damp by the termites. In this way, termites maintain the 100% humidity and constant temperature of 29–31˚C required for successful production of eggs and young. (These conditions are exploited by monitor lizards, who seal their eggs inside termitaria for safe incubation.)

After the rains, when conditions are right, the queen produces a reproductive caste of winged males and females – known as imagoes – who leave the colonies in huge swarms to mate, disperse and establish new nests. Mass termite 'emergences' are one of the bonanzas of the bush, offering a seasonal feast to everything from frogs and spiders to kites, falcons and tawny eagles.