The coral reefs constitute the oldest of all natural communities, and the ones which contain the greatest diversity of life on earth.
Nowhere else in the world is it possible to find so many different living beings in such close contact, and in such great numbers. It is the most complex aquatic ecosystem on the planet.
Such variety of life makes effective visual communication necessary, to send out signals of warning, confusion or hiding, and so the fish of the coral reef have developed extraordinary colours and designs. This is a beautiful sea, but one which contains many dangers.
There are some four hundred types of coral and over one thousand five hundred species of fish, some of them so incredibly beautiful it seems as if each plant or animal is trying to outdo the others.
But this evolution has been a slower process in the reef than in other, much less stable environments, where adaptations and extinctions are frequent, due to important changes in the ecosystem.
The stability of the reef is not, however, static. Quite the opposite, it is incredibly dynamic. Populations of different species vary considerably, but the overall community is maintained. The important thing is not who performs a given function, but that it is performed by someone.
A multitude of organisms with different capacities to carry out different functions allows the reefs to overcome setbacks that would devastate less flexible communities.
Nonetheless, with global warming and ultraviolet radiation, coral in different places around the world is undergoing a process known as “coral bleaching”, which consists of whitening due to the loss of the symbiotic zooxanthelae, and so many of them have atrophied lower limbs. The origin could lie in the fact that the waters are unusually warm.
The optimum temperature for the growth of coral is between 26 and 27 degrees centigrade. Above this temperature, the coral suffers stress which intensifies and speeds up the bleaching process.