Crown of Thorns starfish a serious threat
IF HOLLYWOOD wanted to create the perfect coral-eating machine, it would be the Crown of Thorns Starfish.
This starfish is considered a serious threat to the Great Barrier Reef.
According to research by the Australian Institute of Marine Science, coral cover on surveyed reefs has declined by about 50% over the past 30 years.
Crown of Thorns starfish were responsible for almost half of this decline.
The adult starfish is a voracious predator that eats coral polyps. The average size is 30-40 cm. They have up to 21 arms and are covered in sharp, poisonous spines.
When feeding, the starfish climbs onto the coral using the large number of tube feet on its underside.
It then extrudes its stomach out through its mouth over the coral surface and secretes digestive enzymes that allow the starfish to absorb nutrients from the liquefied coral tissue.
The Crown of Thorns starfish is native to coral reefs in the Indo-Pacific region.
On healthy coral reefs, the starfish plays an important role, as it tends to feed on the fastest growing corals such as staghorns and plate corals, allowing slower growing corals to form colonies.
This helps increase coral diversity.
However, cyclic outbreaks of the Crown of Thorns starfish occur approximately every 17 years.
There have been four documented outbreaks on the reef since the 1960s, with the latest starting in 2010.
Scientific evidence indicates that these outbreaks are associated with poor water quality.
Flood plumes during the wet season can carry additional nutrients and sediments into the reef.
This promotes plankton blooms, which increase the food for many animals including Crown of Thorns starfish larvae.