Marine bioligist Evie Callandar looks out over her office.
Marine bioligist Evie Callandar looks out over her office. Melanie Plane

Surrounded by parrot fish poo, and other weird reef facts

EVIE Callander has a passion for discovering the Great Barrier Reef. Evie completed a Bachelor of Marine Science before making a beeline for the Coral Sea. For the past 18 months the 22-year-old has worked as a marine biologist, trip director and dive instructor for Coral Expeditions. She revealed her five favourite "secrets of the reef".


CREATING SAND: Have you ever wondered where sand comes from? Evie has the answer. "Parrott fish have a really strong beak, teeth and jaw and they like to eat coral polyps and algae so they scrape it off the sides of coral, leaving white scratch marks," Evie said.

"They crunch it up, process it and it comes out as fine sand. It is thought that each parrot fish contributes 1-2 tonnes of sand a year which is absolutely massive." A lot of the sand you sit on is actually parrot fish poo."


SEX CHANGES: "With the group dynamics of the clown fish, if there are five clown fish in an anemone the largest is the female and she is the boss," Ms Callander said.

"The rest of the fish will be male. However if something happens to her, the next largest male in the group will actually change sex to female and become the boss."

"Another cool fact is lots of different species change colour and pattern from juvenile to adult phase."


THE ROLE OF CORAL POLYPS: "Sitting on the skeleton of coral are hundreds and thousands if not millions of tiny little animals called coral polyps.

"They are tiny flower-like structures which have a ring of stinging tentacles and a little mouth opening and they emerge from those skeletons and feast on nutrients and plankton in the water and bring it in to the coral, giving it a lot of its nutrients."


SIZE OF THE REEF: "The Great Barrier Reef is 2300km long. Compare it to the next two largest barrier reefs in the world - the Belize Reef off the Caribbean Coast is 290km and Ningaloo Reef off Western Australia is only 280km."

"The GBR covers the size of Germany and it is seen from space."


RAIN ISLAND: "When summer approaches, green turtles home in on different islands on the reef and there is a really special island called Rain Island up in the north which is a tiny little sand island. It is being really inundated by the daily tidal cycle and with the sea levels rising it is continuously losing sand. There are lots of groups of people that are committed to building up that island, taking sand over and conserving it because it hosts up to 70% of the green turtle population."


Marine Bioligist Evie Callandar on board Coral Expeditions II.
Marine bioligist Evie Callandar on board Coral Expeditions II. Melanie Plane