Monty's Year at Gobabeb Training and Research Centre, Namibia

Archive for September, 2010

White Lady Spider

The “dancing” white lady is only one of many uniquely adapted spider species found here in the Namib.  Consider this a first installment…

Named after a famous rock painting in Namibia, Leucochestris arenicola is large (over five inches across) and inhabits long silk lined burrows.  It is found only in the sand sea and the dry Kuiseb Riverbed, and its burrows tend to be located near the base of dune slopes.  Their large holes are covered by an interwoven sheet of sand and silk, which make them very difficult to find.  During the heat of the day the spiders rest deep below ground, but they become active at night.  Positioning themselves upside down in their tunnels, they “listen” for vibrations with sensitive hairs lining their long legs.  When a bumbling creature is heard above, the spider rushes to the surface and ambushes the prey.  Common species taken by white ladies include palmato geckos, beetles, and even other white lady spiders (more on that soon!).

Males traverse long distances from their burrows at night in search of mates.  In order to advertise their presence, they tap rhythms on the surface of the ground with their legs.  If a female is pleased with what she hears, she may exit her burrow and mate but unsatisfactory males can be eaten instead.  I often see the tracks from this tapping behavior while walking in the dunes around Gobabeb, but few people have ever been able to see the behavior which causes it.

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This past weekend I went camping and was lucky enough to find some of this amazing white lady courting first-hand.  The photos capture a cannibalistic female (on top) I found eating an under-performing male (on the bottom).  I also witnessed some tapping behavior, which is featured in the BBC clip below.  The BBC clip covers some of the fascinating research being done by Dr. Thomas Nørgaard here at Gobabeb.


The middle of nowhere.

The expression is absurd.  Used to describe a host of locations, it seems to paradoxically cast certain places outside the fabric of space itself.  Worse yet it suggests these dimensionless worlds have centers!  Hillbillies, wilderness areas, break downs on desolate highways … the phrase carries a lot of associations.  While I am no stranger to the proverbial “middle,” all the remote places I’ve inhabited have left me feeling relevant to in some larger spatial context.  The “middle of nowhere” just hasn’t been an appropriate descriptor.

Until now that is.  Welcome to the Namib Unconformity Surface.  A place defined by absence.  Nothing, nobody, nowhere.  Home Sweet Home.

Seemingly stripped bare the gravel flats are only a small block of a hyper-arid region that stretches the height of the U.S. along the southwestern coast of Africa.  Straddling the Tropic of Capricorn, the plain is surrounded by an overabundance of abstruse spaces.  To the west the frigid waters of the southern Atlantic sweep northward, meeting the sun-baked interior in banks of fog.  The south holds an enormous wilderness of sand, continually sculpted fresh by counteracting winds.  The westward margins blend into mazes of cliffs and canyons that form the base of an escarpment rising thousands of feet into Kalahari.  To the north lies the “Skeleton Coast,” an ominous wilderness of dunes and mountains.  And of course, above and around, a sky that would shame the state of Montana.

Nathan, Gareth, and I had been hiking since before dawn.  Making our own path across this flat netherworld of space, we drift.  There is nothing organic in sight.  The shark-tooth profile of Gungachoab stands out clearly behind us, although the base where we began five hours earlier is obscured by an opaque shimmer of air.  Low on the opposite horizon lies a heat-distorted skyline of orange dunes, extending far beyond what the curvature of the earth allows us to see.  Our destination, the twisted and fractured bedrock of Swartbank Mountain, looms ominously.  Between pulses of wind the endemic silence is exposed.

The previous afternoon we found a spring hidden among the outcrops and fallen boulders of Gungachoab’s long ridge.  One of seven in the region, its pathetic seep endures a never-ending siege of evaporation.  It manages to hang on, but barely; the salinity of the shallow pools hovers at about six times that of seawater.  Yet this water teems with life.  Within and around the centimeter deep pools, halophytic plant species flourish.  Encrusted within plate-like fragments of salt, the spoor of springbok, spotted hyena, black backed jackal, and ostrich are preserved. Colonies of green algae live inside pockets of salt crystals, perpetually covered by translucent sunshields.  A rare wolf spider darts between pockets of salt hunting for flies and water insects.  Only ever observed at these isolated springs, the species has never been formally described or studied.  In the clefts of rocky slopes, owl pellets and sun bleached bones of gerbils, chameleons, and rock hyraxes reveal a haunt of top predators.  And there is us, three blissful Homo sapiens, uniquely maladapted to this place yet enjoying a damn good sunset all the same.

The following morning we awake to the chill of humid air and a strong southeasterly.  It is only quarter past five, but we have a long walk ahead of us.  By sunset we need to be on the far side of Swartbank Mountain, a distance of 25 kilometers or so, for our rendezvous with Gareth’s wife and our ride back to Gobabeb.  As we hike towards our prepared water cache, the moon, just past full, sheds the landscape in an unsaturated monotone.  From our vantage on the low ridge the mass of an approaching fog bank can be seen riding the coastal breeze from miles away.  Its periphery arms stretch ahead of the main mass like legions of an invading army.

An hour later, our bottles now dripping with cold water, we push off from the inselberg into the beyond.  We orient vaguely towards Swartbank but the shape is obscured by fog, the advancing brink now only a few hundred meters away.  On the opposite horizon the orange ball of a sun breaches, still cool but intensifying by the second.  The cloud halts.  Moments later it begins it’s retreat.  High on the day’s arrival, we sprint towards the barrier until our visibility is reduced to a few meters.  The sun’s low-angle light ricochets off water droplets ethereally.  Mica crystals sparkle.  Lichen colonies, inconspicuous before now, adopt a microscopic vibrance.  The sun burns though.  We are exposed.

From the plain Gungachoab and Swartbank appear to float ship-like from the plain, their hulls enshrouded in fog.  Like all outcrops punching through the Namib, their scars attest to an epic worthy of Calliope.  O Muse!  Tell us a tale of Precambrian orogenies, cratonic movements, recumbent foldings, imbricate thrusting, intrusions, emplacements, and aeolian processes!  Sifting through time incomprehensible, the story begins half a billion years ago as tectonic fate unites star-crossed continental land masses.  Compressing sediments, a mountain chain rises from the depths of the Iapetus Ocean.  Life follows suit, trading watery homelands for a chance at new niches.  Myriad taxa, ever radiating in spirals of interconnected selective pressures, transform the region over hundreds of millions of years.  Sediments accumulate.  By the early Cretaceous crustal wanderlust rumbles again, and the Gondwanan plates pull apart.  As the subterranean cores of ancient mountains torturously split, dikes of molten rock suture the wounds.   On the surface, Atlas, the long awaited son of Iapetus, floods into the expanding cleft.  Erosion and aridity take hold of southwest Africa as the two land masses drift further and further apart.  For the first time the stubborn cores of the ancient mountains are uncovered.  As their earthly shawls unravel grain by grain, inselbergs (island mountains) are left behind as naked sentinels in an empty land.

But such macroscopic drama blurs details.  Stop and smell the biotic crust!  Interwoven in the porous gypsum sub-layers are countless combinations of lichen.  Each “species” an association of algae and fungus, the symbionts stabilize the surface against strong winds.  Crustose forms perched on the summits of larger stones intercept low flying fog droplets in mid-air.  The undersides of translucent quartz holds visible sheets of cyanobacteria, photosynthesizing through the rock while absorbing the moisture that collects around its margins.  As we walk we audibly compress the ground.  Our footprints here could last months.

Closer inspection of the dull gypsum crust reveals endless variety.  Larger bits of marble and dolerite feature amidst crystals of rose quartz and mica.  Between blocks of calcrete pebbles of innumerable variants can be found: granite, schist, copper, and garnets.  In one spot pearly fragments of ostrich shells adorn the matrix.  A black and white bicolor beetle scuttles across the surface.  Tiny black wells encircled by a careful arrangements of quartz pebbles reveal the lairs of corolla spiders.  Using the stones to enhance the vibrations of blundering ants or termites, the spiders wait for prey deep below the surface.  Larger burrows slope diagonally into the earth.  These form the homemade amplifying chambers of barking geckos.  Only used on warm calm nights, three different species compete to woo females with different variations of percussive clicks.  Termite species shift untold sand granules, constructing subterranean realms out of the remnants of ancient monuments.

Unfortunately this sand also holds a richness that is less easy to ignore.  Approaching the base of Swartbankberg and the end of our hike across the flats,  a plume of black smoke erupts from a heat distorted source.  Uranium prospectors.  At concentrations of a few hundred parts per million the Namib gravel plains hold some of richest deposits on the planet.  Rigs like this one scour the land, drilling boreholes hundreds of meters deep.  While a number of mines have been active in this region for decades, recent years have seen concession after concession of this “protected” landscape doled out to multinational corporations.  Companies awarded exclusive prospecting licenses search far and wide for profitable deposits, marking the map for further development.  One such place, a mere 5kms from Gobabeb, has remained quiet.  For now.

In order for any operation to be economically viable enormous areas must be churned and processed leaving behind holes measured in cubic kilometers.  Far more impressive than the lowly burrows they replace, humans’ evolutionary legacy can be seen from outer space.  Radioactive dust is suppressed with millions of liters of fresh water drawn up from plummeting aquifers.  No worries, each mine will only last a few years before the exhausted deposit forces a self implosion.  “Environmental Impact Assessments” precede the dynamite, capturing unidentified species for the next generation.

I fear for this place.

Uranium prospectors from the top of Swartbankberg