The Formation of Coral Reefs

Coral reefs are 'living rocks'. They are inhabited by animals - different kinds of cnidarians, which contribute to the formation of a reef by forming colonies. Every skeleton of the colony is connected to another skeleton by soft parts. Gradually, one organism after the other dies, but the chain carries on and on. The reef grows further outwards and upwards. Lime red algae, which look like pink daubers, are important reef builders as well. They produce limestone, which reinforces the reef like mortar. Young organisms live on the dead organisms of the colony that has already calcified and reproduce on their turn.

The skeleton of an entire dead colony is called coral, the single organism corallite.

The Great Barrier Reef is so big that it can even be observed from the moon. Despite the name, it is not one big, connected reef, but rather a wickerwork of many reefs that spread along 2000 km parallel to Australia’s northeast coast.

Each coral species grows differently. A great variety of colours and shapes are formed, ranging from hills, plates and big panels to branch-like and even fan-like structures.

In the reef, numerous creatures can be found, from tiny jellyfish up to gigantic sharks.

The coral reef is also known for its symbioses. Fish sometimes gather at the reef and wait together for certain prawns or hogfish. These creatures 'clean' the fish and feed on dead tissue or parasites. Both have an advantage. The 'cleaners” get food and the fish get rid of the parasites.