Suspending suspended animation – Namib desert

This is the eighth in a series on the Namib Desert by Joh Henschel of EnviroMEND. The Namib’s wonders have many forms, some of which are tiny, easily overlooked creatures and processes such as the ephemeral puddle and its microfauna.

There are few things more delightful than experiencing rain in the desert, especially when the previous rain fell a year or as much as a decade ago. With pomp and circumstance, preceded by whirling gusts of dust, clouds sail over the Namib, heavily pregnant with moisture, accompanied by blazing lightning and drumming thunder.

The confusion abates when the first heavy drops spatter in the dust, dotting the ground here and there, then inundating it completely. Next the clouds let loose their bounty, filling every nook and cranny of the gravel plains. Then, just as the water rises above the ankles, the clouds close their gates. Like an afterthought, a few more drops tinkle down as the finale, and the show is over, leaving the desert air washed sparkling clean. There are few thrills greater than standing, soaked to the skin, in the aftermath of a desert rainstorm witnessing the reawakening that ensues.

The surface layer of water slowly seeps into the ground or gathers in sloping drainage lines, running off past impeding dwarf shrubs. However, a few scattered, shallow, round depressions with compacted earth – perhaps formed by zebras sandbathing or ostriches nesting – retain 10 to 15 centimetres of rainwater, which will take 10 to 15 days to evaporate. The mud at the bottom of these basins begins to stir, hardly perceptible except to the trained eye, as some of the grains of sand reveal their true identity. They are in effect minute eggs, now popping open, to allow a miracle of ‘instant life’ to emerge from the mud.

In a few days time the puddle starts wriggling and writhing with a diverse assortment of creatures. Fairy shrimps dance elegantly in the water with flitting movements, reminiscent of fairies on the wing. Seed shrimps, encased by two oval shells, resemble stunted submarines. The puddle cocktail also comprises oar-foot shrimps, clam shrimps, water-flea shrimps and tadpole shrimps, not related to each other. They are joined by dragonfly nymphs and midget maggots, emerging from eggs laid in the puddle by passing adult insects. A couple of marbled rubber frogs emerge from a deep recess and discharge eggs that hatch into tadpoles, which in turn parade through the water in formation.

These unusual desert creatures mean business. They forage vigorously, tearing at mats of algae, stirring the mud and sifting the nutritious soup with grabbing strokes and pulsating mouths. They gobble all they can, including each other and each other’s eggs, while doing their best to avoid being gobbled themselves. Nimble, popeyed tiger beetles with a metallic shimmer snatch any creature that ventures too close to the shore. Despite the losses, members of this menagerie grow and multiply remarkably quickly, and then outpace the only-too-obvious limit. As they increase, the pool diminishes. The water dwindles further as birds, springbok, gemsbok and foxes drink, and what’s left rapidly evaporates. The rubber frogs disappear, digging themselves deep into crevices. By the time the pool dries, the shrimps have laid numerous eggs, which now become dormant, hardening into living particles of desert dust. All there is to do now, is to wait for the next rain.

For these secret puddle creatures, the desert is a wet place. When it reverts to its normal arid self, the puddle menagerie abides its time in suspended animation, waiting without suspense for dry conditions to be suspended.

 This article appeared in the May’12 edition of FLAMINGO Magazine.