Great Barrier Reef is about 500,000 years old. Currently 400 species of coral live on there.

Sea snakes do not have gills. They breathe with lungs. So they have to go to the surface to expose their nose to air.

Shark families have evolved themselves since about 4 million years ago.

Few of them are dangerous to humans such as tiger sharks, bull sharks and great white sharks, but most of them are gentle.

Stingrays are relative of sharks. They feed on molluscs, crustaceans and small fish in the Coral reefs.