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Monday, August 15, 2011

Coral for dummies

What is a coral actually? Few decades ago most of the scientific communty still thought corals were pieces of rock or plants. If you look to a dead coral washed up on the beach you'd probably arrive to the same conclusion, or if you don't pay attention while diving you may think they're simply a type a marine plant, even a picture of some corals without an aquatic background could remind you of a fungus . I don't blame anyone for that, for thousand of years people used to think the Earth was flat and that our planet was the center of the solar system.
The common saying: All roads lead to Rome also proves that romans thought they're were situated in the middle of the world. Without adequate tools, it's hard to get an accurate idea of what we are looking at. Now we're are absolutely sure our planet isn't flat and neither in the center of our galaxy, nor are the corals plants or rocks.

Corals are in fact sessile animal forming colony, all small units are polyps. Like a lot of marine invertebrates forming shells the corals have the capacity to do biomineralisation or calcification. By this amazing process they're able to absorb the calcium carbonate dissolved in water and and excrete it to form a exosqueleton, a bit like bones but outside they're body. Corals also bear zooxanthellea, a microscopic algae, who capture the energy from the sun and transforme it through photosynthesis into carbohydrates. The polyp receive part of it and exchange it for protection and nutrients. For millions of years, corals have been building reefs made of calcium carbonate offering us right now probably the most diversed ecosystems of the world. But corals around the world now show many signs of distress; diseases, important bleaching, overcompetition with algae plus the damages caused by human activity. How will the ecosystem react with a weak reef? That's one of the questions our GVI expedition is trying to figure out by monitoring the corals and the fish community.