Elongate giant clam

Tridacna maxima

Guardian: Karin McKirdy

Elongate Giant Clam

Why are corals and clams so colourful?

The colour is created by the selective absorption of light by pigments (they absorb some colours and reflect others). There are a variety of pigments or molecules and they have various functions but corals and clams are so bright or fluorescent because they have crystalline pigments. These pigments have the atoms aligned like crystals, that are so tightly packed that they reflect damaging solar radiation and in doing so create the sparkling glimmering colours of the reef.

This means that when you are snorkelling or diving you are flying over millions of crystals, over living, breathing, crystal skin. No wonder it is so magic.