Crown of Thorns Starfish
Crown of Thorns Starfish in the Solitary Islands Marine Park
What is Crown of Thorns Starfish?
Crown of Thorns Starfish (COTS) is a coral-eating starfish native to the Pacific region, typically occurring at very low densities of less than one starfish per hectare.
When COTS numbers are low, coral reefs can recover from damage caused by feeding. However, if COTS densities increase to a point where a coral reef can no longer keep up with the damage caused, it is classed as an outbreak.
Crown of Thorns Starfish in the Solitary Islands Marine Park
One species of COTS, Acanthaster cf. solaris has been observed in parts of the Solitary Islands Marine Park in small numbers for many years.
Acanthaster cf. solaris
In late 2024, an outbreak of two COTS species, Acanthaster cf. solaris and Acanthaster brevispinus was reported in the marine park for the first time. The Department of Primary Industries and Regional Development (DPIRD) controlled over 150 COTS to protect coral diversity at North Solitary Island.
Acanthaster brevispinus
Control of COTS above feeding scar
Warmer waters and stronger currents associated with climate change are likely to see an increase in tropical species like COTS in future. Surveillance and monitoring for COTS continues to support a fast response to any future outbreaks.
How can you help?
Report any sightings of COTS to help DPIRD quickly identify any outbreaks and protect coral reefs.
COTS spines are toxic, painful and pose a significant health risk. It is important that you do not touch or make contact with COTS.
Download a brochure with photos of COTS.
If you see a COTS in the Solitary Islands Marine Park or on any other NSW reef, please report the sighting to DPIRD as soon as possible by email to solitary.islands@dpird.nsw.gov.au, or phone on 02 6691 0600.
Photos and details of location, date, time, depth, species and numbers are helpful if possible.
