Life on the coral reef: when species live together and help each other out

Status of the relationship: Mutualism - "Win-win" situation. 

The best-known inter-species relationship is that of the clownfish and its anemone. The little fish settles in pairs within the anemone, barely moves away from it and reproduces there. It is protected from the anemone's stinging tentacles by a mucus that covers its body. In exchange for the protection it provides, the clownfish defends the anemone's territory, cleans it, keeps predators away if they get too close and provides it with food.

Status of the relationship: Mutualism - "Win-win" situation. 

In the coral reef, cleaner shrimps - like their "colleagues" the bluestreak cleaner wrasse - perform an essential function for the fish, ridding them of parasites and dead skin.

They feed on this waste and offer the fish a genuine "cleaning service". 

Status of the relationship: Mutualism - "Win-win" situation. 

Another surprising relationship is that between the goby and the pistol shrimp. They are two roommates who share a burrow dug by the shrimp.

The goby keeps watch at the entrance to the burrow and alerts the shrimp, which has poor eyesight, if there is any danger.  

*Mutualism is an interaction of mutual benefit.

Status of the relationship : Symbiosis 

If there is one relationship that is essential to coral life, it is that between coral and zooxanthellae. This micro-algae, which lives in the coral's tissues, provides oxygen and carbohydrates, essential for its growth.

In return, the coral provides the zooxanthellae with nutrients and shelter.