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IN 1938, Henno Martin and Hermann Korn, two young German geologists
working in South West Africa, were threatened with internment by Jan Smuts’
pro-British Empire government – as were the rest of the German community
in the South African colony. Having left Europe in the first place because
they wanted ‘no part in the mass suicide of civilised peoples’, they had
no intention of sitting out the coming war in a prison cell, so they loaded
their lorry and headed into the sun-struck wastes of the Namib desert.

Martin and Korn survived there for nearly three years as fugitives,
living on their wits and becoming increasingly beguiled by their harsh desert
refuge and its strange variety of inhabitants. Since then, many other scientists
have been equally enthralled by the Namib – among them an Austrian entomologist,
Charles Koch, who founded a permanent research station there in 1963.

Koch, an expert on the taxonomy of desert insects, first visited the
Namib in the mid-1950s as a member of a scientific expedition. So excited
was he by the number and variety of tenebrionid – or ‘tok-tokkie’ – beetles
he found scuttling across the scorching dunes, and seeming to ‘swim’ through
the sand on the slip-faces, that he resigned his job in Germany and moved
to South Africa so that he could visit the Namib regularly.

Working for the Transvaal Museum and funded by the Council for Scientific
and Industrial Research, Koch explored most of arid southern Africa, discovering
in the Namib desert at least 200 species of tenebrionids, most of which
showed extraordinary adaptations to their environment and were endemic to
the area. (These included the only white tenebrionid yet discovered.) By
contrast the tenebrionid species he found in the nearby Kalahari Desert
tended to be less exclusive.

In its 27 years of existence, more than 1500 scientists from around
the world have visited and worked at the Desert Ecological Research Unit
of Namibia, which Koch founded at Gobabeb (‘The Place of the Fig Tree’)
on the banks of the rarely flowing Kuiseb river in the heart of the desert.
DERU, as the station on the site of an abandoned Hottentot village is known,
has generated more than 500 scientific papers and has had the rare distinction
of making the cover of both Nature and Science magazines in the same year,
1976, with papers on the extraordinary ways in which two different species
of tenebrionid beetle make use of fog water.

Apart from the fact that the biotic community in a desert is ‘relatively
simple’ and processes are easier to identify than in more moderate areas,
the Namib has several features that make it particularly attractive to scientists.
A long, narrow ribbon that stretches along the entire western coastline
of Namibia, this desert is relatively small (one thirtieth the size of the
Sahara) and easily accessible. Sandwiched between the Atlantic Ocean and
Africa’s Great Western Escarpment, it has a tremendously steep climatic
gradient from west to east, ranging from an average rainfall below 15 millimetres
at the cool coast to about 100 millimetres near the escarpment, with the
area in between experiencing the most extreme fluctuations in temperature
and humidity. While the southern part of the desert is in Africa’s winter
rainfall belt, the north is in the summer rainfall belt. The different climatic
combinations allow a comparative approach in scientific research.

Besides its climatic variety, the Namib has a number of clearly defined
physical environments that show up spectacularly in satellite photographs:
several stretches of rippling sand dunes are divided from flat gravel plains
by ‘linear oases’ – river courses, dry most of the time, that cut across
the desert from the mountains to the sea. (The march of the dunes, which
shift at rates of between 1 and 100 metres a year depending on the strength
of the wind, is checked by the occasional flowing of the rivers.) Such a
range of conditions and habitats has given rise to a particularly wide variety
of plants and animals that, isolated between the escarpment and the sea,
have evolved undisturbed for millions of years. Many species are found nowhere
else on earth.

Koch, who died in 1970, believed the Namib to be the oldest desert in
the world, but this is still a matter of hot debate. Some date it back to
the breaking up of the super-continent, Gondwanaland, about 130 million
years ago. Others date it at 80 million years or even less, when, they believe,
the climate of the area has fluctuated no more than between semiarid and
the hyper-aridity of today. During that time the landscape will have changed
continually with variations in the climate.

One of the unique and most fascinating features of the Namib is the
presence of an ancient dune desert, in fossilised form, beneath the current
active dunes that stretch from the Kuiseb to the Orange River. Dating back
between 40 and 20 million years, these ancient dunes cover roughly the same
area as the present dunes, and appear to have been formed in the same way:
sand carried from the highlands of Lesotho by the Orange River to the sea
was washed on shore and blown northwards by the strong southwesterly winds
that prevailed then as they do today. Furthermore, there is evidence in
the fossil record of plants and animals living then that show remarkable
similarities to some present day forms, such as termites, beetles, and even
the eyeless, sand-swimming golden mole.

The scientists believe that climatic and environmental conditions of
the Namib as it is known today have been relatively stable for at least
5 million years, one of the main influences on both being the cold-water
upwelling system of the Benguela Current.

Established 10 to 7 million years ago, the Benguela Current, flowing
northwards from the Antarctic, is responsible for one of the most important
features of the Namib – fog. On an average of 60 days a year, fog, created
by moist air from the Atlantic condensing as it passes over the icy waters
of Benguela, rolls inland during the night for up to 100 kilometres. This
is the Namib’s life-blood – the main source of free water for hundreds of
species of plants and animals, many of which have developed intriguing ways
of using it.

The head-standing beetle, Onymacris unguicularis, for example, creeps
to the crest of the dune when fog is present, faces into the wind and stretches
its back legs so that its body tilts forward, head down. As the fog precipitates
on its body and runs down to its mouth the beetle drinks, taking on board
sometimes as much as 40 per cent of its original weight in water. Normally
active on the dune surface during warm daylight hours, this beetle will
emerge from its refuge in the sand during the cold night or early morning
to take advantage of the fog before the fierce sun rises and evaporates
the moisture.

Three other species of tenebrionid beetle found in the dunes close to
Gobabeb construct shallow trenches to trap fog water. In digging their trenches,
which may be a metre or more long, Lepidochora discoidalis, L. porti and
L. kahani create two parallel ridges above the sand surface. These ridges
gather moisture from the fog as it blows over them, and may contain as much
as 10 per cent water by weight, compared with 4 per cent for the flat surrounding
sand. The rather flat, button-shaped beetle extracts this water as it returns
along the trench a while later.

Other animals not specifically adapted to take advantage of the fog
nevertheless use it for their water requirements; snakes and lizards drink
their droplets from their skin, and many insects drink the drops that collect
on plants and rocks.

Arthraerua leubnitziae, the very characteristic dwarf shrub of the Namib
plains, is entirely restricted to the fog belt along the coast, and appears
to have some extraordinary mechanisms for extracting moisture from the air.
The kind of dreary little plant that most people pass without a second glance
is the subject of fascinated research by Gobabeb’s visiting botanists at
the moment.

A few short-lived leaves appear after rain, otherwise the plant above
ground consists only of green stems. In cross section these stems have deep
grooves, radiating from the centre like the spokes of a wheel and harbouring
the stomata. This arrangement cuts down water evaporation, while there is
some evidence that salt crystals on the surface of the plant are instrumental
in extracting moisture from the atmosphere. However, research is continuing
to establish if this is in fact the case. From excavations it appears that
the roots can be dormant for long periods, and that they may serve to store
water taken up by the stems. After rain small roots and root hairs regrow
rapidly.

Another aspect of the slow-growing and long-lasting A. leubnitziae that
is intriguing scientists is the presence of apparent growth rings. These
are thought to relate to rainfall and could thus reveal a picture of the
desert climate before rainfall records began in 1880.

As well as being able to make use of whatever moisture there is, conserving
water is also very important in a desert environment. Many of the tenebrionid
beetles secrete ‘waxes’ – long chain hydrocarbons mostly saturated with
hydrogen – which cover the surface of their bodies in a waterproof layer.
Researchers have found that evaporation from the cuticle of one species
of dune beetle exhibiting the waxy bloom is as low as 0.11 milligrams per
hour – one of the lowest rates recorded for any animal. The bloom dissolves
quickly when humidity is high.

The sabre-horned gemsbok, Oryx gazella – a Namib-dweller that can survive
for weeks without drinking – simply ceases to sweat when deprived of water.
At such times its body temperature, normally around 39 Degree C, might reach
as high as 45 Degree C and be sustained at this level throughout the heat
of day. The animal has an intriguing mechanism for protecting the brain
from such damaging temperatures: in a network of fine blood vessels, known
as a rete, at the base of the brain, heat is exchanged between the hot arterial
blood from the heart and cool venous blood draining from the nasal sinuses.
As the two bloodstreams flow through the rate in opposite directions and
close to one another, the arterial blood is cooled by several degrees before
entering the brain.

The ostrich, commonly seen as a big blur in the shimmering heat of the
plains, is able to conserve as much as 25 per cent of its daily water turnover
by exhaling unsaturated air. Whereas most animals breath out saturated air,
researchers at Gobabeb have found that the air exhaled by ostriches has
a relative humidity of only between 80 and 85 per cent. No one has yet been
able to discover the mechanism behind this extraordinary phenomenon.

Baboons living in the Kuiseb Canyon have excited particular interest,
too, because the Namib is the most arid environment in which any non-human
primate has ever been found. Studies from everywhere else report that baboons
drink daily, but scientists have very recently observed a Namib troop going
without free water for close on a month. They appear to exist on a knife-edge
of survival, eating plants with a high moisture content, chewing the moist
bark of acacia trees, and totally modifying their behaviour to minimise
heat stress. The young do not play; males do not chase females; all day
the animals rest in whatever shade they can find, scratching away hot surface
sand before lying belly-down like dogs.

Many of the desert life forms, while adapted to surviving the driest
periods, are also ready to respond to rain whenever it should fall. This
was demonstrated most graphically in 1976 when 100 millimetres of rain fell
near Gobabeb. As the dunes darkened under the downpour, DERU’s director,
Mary Seely, and an assistant excitedly snapped away with their cameras.
‘We were lucky to have already initiated a study into the simple population
dynamics of the sand dune environment and how it changes throughout the
year,’ says Seely. ‘After the unusual rains we were able to repeat the measurements
to see how a naturally very arid area responds. A lot of germination went
on and in time we found that there had been a 56-fold increase in the standing
biomass of plants, and a several hundred-fold increase in the animal population.’
The rain fell between January and March 1976 and the population of tenebrionid
beetles peaked the following November and December. The unusually rich grazing
also attracted a herd of 120 gemsbok to the Gobabeb area; today they are
again a rare sight.

‘One of the most important things to come out of our research into the
effect of the rain was that a natural area which has not been destroyed
in any way can respond tremendously. By contrast, heavy rain on land that
has been damaged by overgrazing or the like causes erosion and all kinds
of negative effects,’ says Seely.

The other elements – heat and wind – play an equally important role
in the life of the Namib. Many of the desert’s creatures survive the extreme
temperatures by exploiting favourable micro-climates in the environment.
Small animals on the plains retreat from the fierce sun under rocks, pebbles
and plants, while on the dunes such creatures as beetles, lizards and spiders
disappear into the sand in search of more favourable temperatures or climb
into vegetation. The free-moving sand on the slipface of the dunes is not
a suitable medium for burrowing, and many of the species that live there
literally ‘swim’ through it. Many come to the surface only to eat, drink
and mate, while a few species (such as the golden mole) live almost entirely
within the sand.

Despite its obvious importance, very little is known about the environment
beneath the surface, or the interactions that occur there. To a large extent,
scientists have been constrained by lack of affordable or sufficiently sensitive
instruments for measuring such things as subsurface humidity. ‘Most probes
work very well between about 10 and 90 per cent relative humidity, but what
we want are the extremes,’ explains Seely. ‘We want to know what’s happening
between 90 per cent and 100 per cent during fog, or at the other end of
the scale when the hot east wind is blowing and the air is very dry.’ Furthermore,
no one has yet come up with a device that will hold steady the loose sand
on a slipface while scientists dig below the surface.

Seeking cooler temperatures within the sand is not the only way of coping
with the extreme heat on the surface. The lizard Aporosaura anchietae does
a ‘thermal dance’, lifting two feet off the ground for a few seconds at
a time in alternate fashion (left front foot with right rear foot, and vice
versa). The long-legged beetle Onymacris plana can lower its body temperature
by up to 10 Degree C by running across the scorching sand at a speed of
1m per second; while other beetles take advantage of the steep temperature
gradient immediately above the desert floor by stretching their hind legs,
or ‘stilting’.

Many deserts plants are ephemeral but have seeds that can withstand
extreme temperatures and remain dormant for decades until the right conditions
arrive for germination. Birds that visit the desert can escape unfavourable
conditions by migrating. However, several species besides the ostrich are
well adapted to desert living. One of the most extraordinary adaptations
is exhibited by the sandgrouse, Pterocles namagua, which eats mainly small
seeds and nests often on the waterless gravel plains. The male bird saturates
his belly feathers at a water source, sometimes up to 40 kilometres from
his nest, and transports water in this way back to his chicks who thrust
their beaks under him and drink as if from a sponge.

Winds of change

The third element, wind, fashions the desert environment. Besides sculpting
the dunes into distinctive shapes, it maintains the loose condition of the
sand which is so vital for the animals that need to retreat to the subsurface
for survival. Furthermore, many of the beetles are detritivores; they depend
on the wind to carry the dead plant and animal material on which they feed
across the dunes, and are only active above the surface when it is blowing.

The wind also plays a part in the scant rainfall of the Namib. Most
of the year a strong southwester blows, resulting in a cool inversion layer
over the desert that reduces the turbulence necessary for cloud development.

And of course the wind transports the fog which, besides being a major
source of water for living things, has helped create the distinctive gravel
plains of the Namib. Occasionally the nutrient-rich Benguela upwelling brings
sulphur to the surface from the mass of decomposing plant and animal life
at the bottom of the sea. Carried on shore in the fog, this is the source
of the sulphate in the gypsum that covers the gravel plains.

Nothing like as spectacular as the dunes, the gypsum-covered plains
are no less characteristic of the Namib. Nor are they any less interesting
to science, though until recently most research was concentrated on the
dunes, because these were thought to represent the most extreme environment
for living things. The gravel plains support several hundred species of
lichen, many of which are endemic and thought to include individual plants
that are thousands of years old. The lichen fields of the Namib, which still
hold many secrets, are now recognised as unique in extent and variety.

Another ancient and mysterious inhabitant of the gravel plains is the
Welwitschia mirabilis, a botanical paradox which, since its discovery in
1859, has excited the curiosity of more scientists than any other plant.
The Welwitschia is grouped among the conifers but shares some characteristics
with flowering plants and also with simple club mosses. A single plant may
live for over a thousand years, its two fibrous, strap-like leaves curling
into fantastic shapes along the ground. They are the longest-lived leaves
of any member of the plant kingdom.

In order to minimise water loss, Welwitschia in the driest parts of
the desert open their stomata and take in carbon dioxide at night, completing
the process of photosynthesis during daylight hours. Those growing in more
temperate areas, however, photosynthesise in the normal way. The Welwitschia’s
method of pollination is a subject of controversy: once thought to be wind-pollinated,
it now appears that wasps might be the agents but the evidence is not yet
conclusive.

Besides the continuing mysteries of the Welwitschia many other questions
remain to be answered about the Namib. Not least of these, for Seely, is
how DERU will continue to be funded in a newly independent country strapped
for cash. ‘Visiting scientists bring their own finance, and that will carry
on,’ she says. ‘But we badly need funds to maintain the facilities of the
unit, the computers, the long-term data base and the library – all the things
that enhance the effectiveness of research work.’ One possibility, she suggested,
might be for a consortium of interested bodies to support DERU in much the
same way as research in the Galapagos Islands is supported.

Although DERU is a private foundation, the station is within a National
Park run by the Namibian Department of Nature Conservation, which also owns
the buildings at Gobabeb and foots the bill for basic services. Seely knows
that if it is to gain the support of the new government and continue operating
out of Gobabeb, DERU must succeed in conveying the relevance of its work
to an independent Namibia.

Research has always been biased towards basic science, and the unit
has a high international reputation among scientists. But Seely believes
the knowledge they have accrued must be made available to a wider public.
‘We have a tremendous contribution to make because in all Namibia we have
the most information about a certain environmental type – which actually
occupies 97 per cent of the country,’ she says.

She is hoping to do something about what she sees as the ‘serious and
ever-widening communication gap between basic science and people for whom
the information could be useful’ by training science journalists at DERU.
One or two candidates a year – preferably from Namibia – would spend time
at Gobabeb, gaining experience of basic research and an understanding of
the scientific method.

Another plan is to expend the environmental education they already provide
through open days visiting schoolchildren and workshops for teachers. Science
teaching is particularly poor in Namibia, and DERU hopes to offer short-
and long-term in-service training to science teachers. A new post at Gobabeb
is already being negotiated for someone who will incorporate the unit’s
research information into the science syllabi for Namibia’s schools and
create other educational materials.

Another area in which DERU could contribute to the new young country
is in tourism – one of the mainstays of the economy. With its wide horizons,
weird life forms and dramatically changing colours, the Namib is a stunning
place to visit yet few people stop on their way to the sea. Seely is enthusiastic
about encouraging tourism to the desert. But she also calls for careful
organisation and controls: the desert environment is extremely fragile.
Unrestricted driving across the gravel plains, for instance, destroys the
lichens which take centuries to recover. And litter, too, is particularly
damaging to the desert, she explains: ‘In the most arid parts practically
nothing decomposes. Apple-cores and orange peel, and even human faeces,
simply dry up and last almost forever.’

DERU is already producing attractive and much-needed information for
visitors that explains these points. The unit is looking for funds, too,
to prepare a more detailed brochure describing the essential characteristics
of an arid environment, which Seely believes are not well enough understood
or respected in Namibia. Many of the basic principles demonstrated by scientists
at the unit are directly relevant to conservation management, but are often
overlooked. Agriculture is a particular culprit: it follows largely imported
ideas and models that are not in harmony with the land or the climate. Furthermore,
says Seely, farmers frequently blame failures on drought, which is nothing
more than the normal condition in Namibia.

Like everything else in this new young country, DERU is at a crossroads.
The future is uncertain. But Seely is going out of her way, with invitations
to Ministers to visit her desert ‘laboratory’, to see that the research
unit is recognised by those now in power as a unique asset rather than a
luxury or an anachronism.

* * *

Freewheeling spiders spin out of danger

DURING their time in the desert, Martin and Korn frequently came across
footprints of some kind of buck they could not identify. The two scientists
were particularly mystified by the fact that the prints were in clusters
and led nowhere.

Korn provided a working hypothesis: ‘It can only be the trail of the
excessively rare feathered water waddler,’ he said. ‘It never shows itself
in daylight because it feels ashamed when other birds laugh at its silly
feet. It nests in inaccessible rock crevices and feeds exclusively on fudge
and fiddlesticks. On account of its weak understanding it can take only
two or three steps at a time.’

Today it is known that the footprints of Korn’s fictitious ‘water waddler’
were in fact the highly distinctive nest of a sand-burrowing spider, Seothyra.
This spider spreads its web on the surface, leaving the sticky edges open
to catch insects running on the sand. The ‘buck-spoor’ spider, as it is
commonly called, is just one of about 163 spiders found in the Namib, and
is the subject of research by Gobabeb’s resident Spider Man, Joh Henschel.

Another arachnid that Henschel has been studying closely and that shows
particularly interesting adaptations to its sand-dune habitat is the ‘wheeling
spider’, Carparachne aureoflava. In a paper awaiting publication Henschel
describes what he believes is the first conclusive evidence of the use of
the wheel by a member of the animal kingdom.

Carparachne aureoflava, which lives exclusively on the dune slipfaces
of the central Namib, uses wheeling as an effective means of escape from
danger. Its most important predator is the female pompilid wasp, a specialist
spider-hunter that paralyses its prey before laying a single egg on its
body and burying it in the sand. When the egg hatches weeks later, the wasp
larva feeds on the still living, and therefore fresh, spider.

The female wasp spends most of her time searching the dune slopes for
spiders’ silk-lined burrows which she will excavate, sometimes displacing
as much as 10 litres of sand to get at her quarry. When flushed from its
burrow or threatened on the surface by any danger, the wheeling spider does
a short run before curling its legs into semicircles, flipping its body
sideways and rotating wheel-like at high speed to get away.

The spider relies totally on gravity for momentum, and Henschel has
recorded speeds of 0.5 to 1.5 metres per second and rotation rates of between
10 and 44 per second, depending on the steepness of the slope and the size
of the spider.

Wheeling appears to have several advantages over running. It is faster
and can be sustained for longer periods because it requires less energy.
And it blurs the outline of the spider and leaves fainter tracks in the
sand, making it more difficult for the hunting wasp to follow. Disadvantages
of wheeling, however, are that the spider can travel only in the direction
of the slope, and go as far as gravity will take it.

The strategy appears successful. On three occasions he saw spiders escape
from wasps by wheeling, while on three further occasions the spiders that
did not adopt this strategy were captured.

Sue Armstrong is a freelance journalist based in Johannesburg.