Corals

Actually the whole of the Maldives consist of coral. There are no rocks, everything that looks like stone are just remains of dead corals and even the sand is mostly based on coral.

The coral-polyp is an animal and there are quite many different species of them, they belong to the class Coelenterates. The corals are close relatives to anemones and jellyfishes, most of them are just a couple of millimeters big.

Anatomy of a coral The coral's body mainly consists of a tube or big stomach (4) stucket into the limestone (1). The top of the tube - which is both mouth and anus (3) is open and surrounded by stinging tentacles (2).

Nematocyt The coral’s stinging tentacles work in the same way as those of the jellyfish. On the outside one will find a trigger (1). The trigger activates when touched and releases a harpoon (2) filled with venom. The harpoon is fastened on the victims skin with small flukes (3). Most of the Maldivian corals have either small harpoons or very light venom, which means that they are no threat to humans. A few species (e.g. the fire coral) could cause quite a pain.

Usually when we speak about corals we do not think about the animal. We think about the reefs, magnificent constructions made during thousands and thousands of years by the tiny coral-polyp - the greatest of all constructors in the world, man included. Actually a single atoll of the Maldives is a bigger construction, having the constructors size in mind, than any building ever erected by man. The reefs mainly consist of limestone which is produced by the polyp. However, the polyp cannot produce the limestone by itself, it needs the help of an algae (Zooxanthellae) with which he lives in symbiosis. The polyps reside the algae in their own tissue.

A coral-reef is a complex ecosystem very much alike the rain forest. In both systems one will find a big variety of species.

Not only fishes reside on the reef. One will also find mammals (e.g. whales, dolphins), plants (e.g. algae) and reptiles (e.g. turtles and snakes). The animals of the reef live in a big abundance over a relatively limited area, like people in a big town.
And just like people most of the inhabitants of the reef are nice to each other, but a few of them are malicious.

One of the best examples are the cleaning wrasses. You will often see these small fishes cleaning the body of much bigger species, removing parts of dead skin and parasites. Quite often one can even find small cleaning wrasses swimming inside the open mouth of a big moray eel, cleaning its teeth. For us it is amazing the eel does not eat the wrasse, but for both of them it is quite natural. I mean, we do not use to eat our dentists… Another fish, of a totally different species, has developed an appearance which is more or less identical to the appearance of the cleaning wrasse. The bigger fishes needing to be cleaned does not see the difference between the true and the false wrasse which allows the false one to take a bite.

The fantastic and intricate reef community is a wonder of nature. When in the Maldives, or where ever you will find a coral-reef, pay it a visit! It is something you will never regret! Do not worry if you cannot dive. Even skin-diving will let you in to the coral-reef’s amazing world.

Building an atoll

Charles Darwin’s theory about the development of atolls

Millions of years ago there where big volcanic islands surrounded by corals. When the islands began to sink, the corals continued to build the reef upwards. They needed to be close to the surface and the sunlight – otherwise the resident algae would die. Year after year the corals continued there endless constructing activity, building up the reef.
Drilling in the Maldives in 1980 has showed that the reef is more than 2.000 meter thick and that one, underneath would find a volcanic base.

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