top of page

Crown-of-thorns Starfish


Crown-of-thorns Starfish

The crown-of-thorns starfish is a sea star named for the spines that cover its body and arms. These spines are somewhat flexible in life and are used for locomotion and for defense from potential predators. This species is a well-known coral predator, and outbreaks of tens of thousands of individuals have been known to cause serious harm to coral reefs in some areas.


These outbreaks may be a result of overfishing of the crown-of-thorns starfish’s primary predator, the giant triton or they may be a natural phenomenon. These starfish are known to be more successful at preying on large swaths of coral reefs when the corals are already stressed. During times of coral bleaching or stresses caused by human activities, outbreaks of the crown-of-thorn starfish may be particularly destructive. These starfish feed by inverting their entire stomach, through the mouth, and digesting the thin layer of soft tissue off of a coral’s skeleton, right in the open environment, and sucking down the available nutrients.


Historically, fishers and conservationists who feared that crown-of-thorns starfish would permanently damage local reefs have worked together to try to control the population size of this predator. In some places, individuals were chopped in half or into smaller pieces. Unfortunately, this process may have backfi