The Story of Life & the Environment
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The Story of Life & the Environment  an African perspective
The Story of Life and the Environment
A distant galaxy photographed from the Hubble telescope.
A group of women fishing with baskets in the Okavango River, Botswana
A hawksbill turtle swimming over a coral reef off Zanzibar, Tanzania
Californian coast redwoods, the largest trees on Earth

Life in the Oceans

The Earth is often referred to as the Blue Planet - appropriately so, given that more than 70% of its surface is covered with sea water. At an average depth of about 4 000 m, and a maximum of 11 000 m (Mount Everest is 8 848 m high), the oceans provide 99% of the living space on Earth. They are inhabited by representatives of almost every major taxonomic group of organisms, as well as by those that still remain unknown to us. Our knowledge of living marine organisms, as well as their interactions with each other and with their environment, is frequently extremely poor, in contrast to that of terrestrial organisms. Although we know a lot about life in shallow coastal waters, our knowledge diminishes with increasing depth. Fortunately, during the past few decades, new deep-water submersibles able to withstand the immense pressures of the ocean depths have revealed a completely new world to both scientists and the curious public.

Sea anemones come in a great variety of shapes and colours. They are mostly cylindrical, have a centrally placed mouth surrounded by tentacles, lack a hard skeleton and support their bodies by internal water pressure    Osteichthyes: marine lionfish, a striking fish with toxic spines capable of causing painful wounds    A blue whale, the largest animal that ever lived, depicted with a human for scale

Our affinity with the sea stretches as far back as the existence of Homo sapiens. Early humans certainly made use of the riches of the intertidal zone and even the subtidal zone. Archaeological evidence shows that 125 000 years ago, southern African ancestors of the present-day San hunter-gatherers were the first humans to exploit the ocean for food. As their harvests were restricted to mussels, limpets and whelks, they did not utilise even a fraction of the available marine resources. Only thousands of years later (between 60 000 and 40 000 years ago), when humans became resourceful enough to build sea-faring vessels, did we really start to appreciate the vastness and enormous potential of the world's oceans.

Information boards like this one explain the concept of Marine Protected Areas (MPAs) at public beaches along the South African coast

Story of Life