The north-western coastal area of Namibia is an intimidating region to say the least; a region where very little rain falls and very little conventional plant life can be sustained. There are few bushes and almost no trees, grasses or other ground cover, there are, however, the remains of many shipwrecks and it is not difficult to figure where it got its popular name – the Skeleton Coast. Sailors surviving a shipwreck along this coast in days of old faced a tremendous fight for survival.
There is a form of plant life, though, that flourishes in this harsh environment – lichens. Found in relative abundance in “lichen fields” dotted along the coast, these plants grow in such profusion that they add a colourful tint to the otherwise bare rocks; white, green and organge-red seem to be the most prolific colours found here.
So what are lichens? Well, technically they are composite organisms consisting of a symbiotic relationship between a fungus and an alga. They grow in some of the most hostile environments in the world, such as in the cold of the Arctic tundra and in the heat of the Skeleton Coast desert. In these extreme conditions they may be the only plant life present. Just how tough these plants are was demonstrated in 2005 when two species of lichen were sent into space aboard a Russian Soyuz rocket. The capsules in which they were packed were opened and the lichens exposed to the vacuum and extreme temperatures of space for 15 days. On their return to Earth they were found to have suffered no discernable damage whatsoever!
In the lichen fields that we visited on the Skeleton Coast the lichens are found mainly on the bare stones and pebbles that lie there in abundance, but also on the exposed ground. This makes them extremely vulnerable to disturbance by vehicles moving through the area and the damage caused is quite obvious where vehicle tracks are found.
The cells of the algae are capable of photosynthesis, as are the cells of green plants, and convert the carbon dioxide from the air into carbon sugars that feed both the algae and the fungi. Both the symbionts are able to extract water from the mist rolling in from the Atlantic Ocean, and the fungi help in protecting the algae by retaining the water. It is interestng that in this environment neither the algae nor the fungus can exist without its partner.
The shape that is adopted by the lichens varies quite considerably, some looking like small leafy plants (called foliose) and others looking like hard crusts (called crustose) or collections of filaments (called filamentous).
The word algae (singular alga) is derived from the Latin “alga” meaning “sea-weed”; fungi (singular fungus) is derived from the Latin “fungus” meaning a mushroom.