A new study looked at how one of the Earth's oldest reefs was formed 550 million years ago.
The reef, which is now on dry land in Namibia, was created by animals that have hard shells, a University of Edinburgh news release reported.
These tiny creatures first developed the ability to construct hard protective coats and build reefs; the purpose of these reefs was to provide shelter. These were the first creatures to build structures similar to non-living reefs, which form through erosion and sediment deposits.
The team found these ancient animals, called Cloudina, attached themselves to fixed surfaces and to each other by producing calcium in order to form rigid structures. The creatures were tiny filter-feeding creatures that lived on the seabed during the Ediacaran Period. These animals were believed to have had soft bodies until the emergence of Cloudina.
The animals developed the ability to build reefs to protect themselves from the growing threat of predators. They also gave the animals access to nutrient-rich currents as food competition also grew. The development of the hard biological structures, though a process called biomineralisation, is believed to have sparked a boom in the biodiversity of marine ecosystems.
"Modern reefs are major [centers] of biodiversity with sophisticated ecosystems. Animals like corals build reefs to defend against predators and competitors. We have found that animals were building reefs even before the evolution of complex animal life, suggesting that there must have been selective pressures in the Precambrian Period that we have yet to understand," Professor Rachel Wood, Professor of Carbonate GeoScience at the University of Edinburgh, who led the study, said in the news release.
The study was published in the journal Science and was carried out in collaboration with the University College London the Geological Survey of Namibia. The work was supported by the Natural Environment Research Council, the University of Edinburgh and the Laidlaw Trust.
