The Crown Of Thorns Starfish And Scuba Diving
Facts A Diver Should Know When Underwater With Acanthaster Planci
The Crown of Thorns debate has been heated. Some believe governments should spend large amounts of money to rid the reefs of the menace. Others believe nature should take its course.
Crowns of Thorns outbreaks “generally occur at regular intervals” (CRC Reef Research, 2003). The causes of outbreaks are not clearly understood.
If A Scuba Divers Finds A Crown Of Thorns Starfish
When a scuba diver finds a Crowns of Thorns starfish while diving on a coral reef, should the diver kill the animal to prevent it devastating more coral?
The Australian Institute of Marine Science (AIMS) based in Townsville, Australia, recommends leaving the starfish alone. It is found throughout the Pacific region so finding a single starfish in a small area is no justification for killing it. This is especially important in a Marine National Park as all things are protected.
For some divers, it can be distressing to leave the animal to continue devouring acres of living coral. Understanding the Crowns of Thorns starfish is useful to support this approach.
Crown Of Thorns Defence Mechanisms
The Crown of Thorns starfish can grow up to one metre in diameter and up to 21 arms. Its upper body is covered in spines that are coated in a toxic mucous which can easily penetrate a wetsuit. It isn’t fatal but a spine embedded in flesh can be painful. The puncture wound will turn dark blue and result in swelling which could last a couple of days. This may be accompanied by intense pain, nausea and vomiting.
For a spine embedded in skin, soak the area in hot water, then dig out remaining pieces of the spine.
Where Are Crowns Of Thorns Located?
The Crown of Thorns is found throughout the Indo-Pacific region. The furthest south in Australian waters has been on Lord Howe Island and the Solitary Islands. It has been found in the Gulf of California, off the east coast of Africa, and the Red Sea. Around the Japanese islands of Ryukyu about 13 million starfish were once removed during an extensive eradication program.
The starfish can be found anywhere on the reef, though adults seem to stay clear of the surf zone. The giant Triton snail is believed to be the starfish’s main predator, but unfortunately commercial raiders have decimated the snail’s population. Humpheaded maori wrasse are thought to eat the starfish. One species of puffer fish and two types of triggerfish have been observed eating the starfish. One certain shrimp and a worm feed on small adults.
Impact of Crown Of Thorns on Coral Reefs
A coral reef, once infested by the Crown of Thorns starfish, will eventually recover though it will take time. Staghorn and plate coral are top of the starfish menu, and fortunately they are quick growing corals, taking about 12 to 15 years to re-grow. The slower-growing massive corals, like the brain coral, are least preferred.
The female Crown of Thorns starfish releases about 60 million eggs during the southern hemisphere spawning season from December to April.
Crowns Of Thorns And Sportdivers
The first thing a sport diver should do when finding a Crown of Thorns starfish is to determine if the area is a protected zone where the taking of any marine life is prohibited.
The second is to record the sighting and report it to the authority responsible for the marine life in the area.
For scuba diving articles refer to:
Scuba Diving Anxiety and Panic
Crowns Of Thorns Starfish
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Crown Of Thorns Starfish In Staghorn Coral
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