Acanthaster Planci, commonly known as Crown of thorns, is a sea star that acquires its name from the spikes that surround its limbs. Its fairly flexible spikes are employed for movement and defense against possible threats. 

This species is a well-known predator of coral, and in some places, infestations of hundreds of thousands of them have been observed to disrupt coral reefs seriously. The Indo-Pacific area, the Pacific and Indian Oceans, and the west coast of Central America are all home to the Crown of thorns starfish.


A classic starfish has a center circle and spreading arms, which the Crown of thorns is. Even so, it has unique characteristics, including a plate-shaped body, about 21 supple arms, which are opposable, and a high stomach area-to-body mass ratio. The Crown of thorns might be violet, magenta, pinkish grayish, brown with red spine points, green with yellow spine tips, or purple based on nutrition or physical location.

Typical Crown of thorns stuck to a coral
Typical Crown of thorns stuck to a coral

As one could guess, the Crown of thorns gets its name from the long, prickly spikes on the ends of its limbs and top layer, which mimic thorns and form a crown-like structure. The two sets of many tube feet that reach the tips of each arm give it the capacity to grasp objects.


The Crown of thorns’ hue depends on dietary or geographic location. Crown-of-thorns starfish feed on almost any coral, and the population size, sea circulation, and species diversity impact their dietary inclinations and activity patterns. Branching and table corals, which belong to the same genera as those that are most susceptible to bleaching, are what Crown of thorns normally consume most frequently. 

However, Crown of thorns may devour other corals like Porites or foliose corals when branching coral growth is inadequate due to an excess of Crown of thorns or external conditions. Along with eating hard corals, Crown of thorns may also consume soft corals, algae, sponges, and creatures that form encrusting layers.


In the Indo-Pacific region, the crown of thorns is widely distributed. However, it can be found in tropical and subtropical regions that span from the Red Sea and the coast of East Africa well over the Indian Ocean, throughout the Pacific Ocean, and down to the west coast of Central America. The Crown of thorns is probably most prevalent in the region around Australia.

Crown of thorns seemingly morphing into its habitat
Crown of thorns seemingly morphing into its habitat

Wherever hard coral colonies or coral reefs are present in the area, chances are that Crown of thorns is there as it provides plenty of food. It uses its great number of limbs, which are located in separate grooves on the oral surface, to climb onto a portion of a living coral colony. Then, almost to its own circumference, it protrudes its stomach over the top through its mouth.


Depending on the location of each colony, the Crown of thorns spawns periodically in the summertime. Northern hemisphere populations typically spawn between the months of August, whereas southern hemisphere populations typically breed around November and February. The males and females of  Crown of thorns starfish mate by releasing their gametes into the ocean, where they are fertilized. 

Crown of thorns emit compounds that cause organisms close to begin reproducing. But not every member of a population spawns at the same moment. The Crown of thorns will ascend to a high ledge on a coral column before arching its body to lay its eggs. Then it will vigorously swing its arms and jerk its limbs while it releases gametes from 5 openings from the surface of the body.


Crown of thorns have long, venomous spikes to defend them against a variety of predators, yet predation still happens, as evidenced by the fact as many adults as 60% within a population could be missing arms. Crown of thorns juveniles exhibit more enigmatic behaviors and reside in cracks and on the underparts of crevices. 

Particularly large, and vibrant specimen Crown of thorns on top of a rock
Particularly large, and vibrant specimen Crown of thorns on top of a rock

Giant triton shells, White-lined pufferfish, Harlequin shrimp, Triggerfish, and Lined fireworms are natural predators of Crown of thorns. They have stiff, plate-like scales and powerful, sharp teeth that enable them to tear off portions of tissue on a Crown of thorns while fixed on a coral.

Facts about the Crown of thorns

  1. Crown of thorns is the second largest starfish in the world, reaching a length of 3.2 ft.
  2. A single Crown of thorn starfish consumes 107 sq ft of corals annually.
  3. Crown of thorns has eyes on its limbs and a sophisticated visual system.
  4. The Crown of thorns moves at 1 ft per minute.
  5. Crown of thorns’ scientific name, Acanthaster, translates from Latin into “thorny star.”


Should you remove the Crown of thorns starfish?

The Crown of thorns can be an invasive species; discarding or destroying them remains the service you can do to halt outbreaks; however, slicing into the flesh to eliminate them won’t accomplish much because they are known to mend and renew.

What happens if you touch a  Crown of thorns starfish?

Venomous species like Crown of thorns can be lethal if handled incorrectly. The victim feels intense pain right away as the skin is punctured, along with substantial blood and inflammation. Typically, symptoms linger for a short time—between half or 3 hours—before going away.

How long does Crown of thorns starfish live?

Crown of thorns age and enter the elderly stage after 3 to 4 years, while the exact lifespan of these creatures in the wild is unknown. The majority of examined specimens passed away between 5 and 7 years of age and have a reported 8 to 15-year lifespan expectancy in captivity.

Is fresh air toxic to Crown of thorns?

Since clean air is harmful to Crown of thorns and they can’t maintain their breath for extended periods of time, each time they are hauled out of the water, they are drowning from carbon dioxide buildup. This happens because the Crown of thorns transfers oxygen from the water through channels on the body’s surface.

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