Crown-of-Thorns Starfish Facts

Scientific Classification

KINGDOM: Animalia

PHYLUM: Echinodermata

CLASS: Asteroidea

ORDER: Valvatida

FAMILY: Acanthasteridae

GENUS: Acanthaster

SPECIES: Acanthaster planci

Conservation Status

A Crown of Thorns Starfish feeds on a bleached, dead hard coral on a tropical reef

The crown-of-thorns starfish is one of the largest starfish in the world having a diameter of anywhere between nine inches to three feet!

The crown-of-thorns starfish can have anywhere from 7-23 arms! Similar to other starfish species, the crown-of-thorns starfish can lose one of its arms if it is hurt or in times of stress; however, it can regrow this limb within six months. The entire upper body of the starfish is covered in sharp spines that can grow up to two inches long, with each spine being encased with epidermis.

The crown-of-thorns starfish has toxic spines that are so sharp, they can easily pierce a wetsuit. Luckily, this starfish has no method for injecting the toxin, and it can only be transferred through touching the spines directly.

Even though the crown-of-thorns starfish is most commonly found in Australia, they reside on what is known as the Indo-Pacific distribution. This includes all waters between the Red Sea, Indian Ocean, Pacific Ocean, and onto the west coast of Central America.

The crown-of-thorn starfish is known as a corallivore, which means they primarily feed on coral polyps. They can do this by closely attaching themselves to a section of living coral and then the starfish will extrude its stomach onto the coral’s surface. Then, their stomach secretes digestive enzymes to absorb nutrients from the coral. An individual starfish can consume up to 65 sq. ft of coral reef per year!

Mating season for the crown-of-thorns starfish is usually between October and March depending on the area and climate. Instead of mating through direct contact, the male starfish will release sperm into the water column while females will release eggs. In fact, female crown-of-thorns starfish can produce up to 65 million eggs during one season! The fertilized eggs will go from eggs, to larvae, plankton, and then adults.

The toxin this starfish produces not only affects people, but it can also harm marine life as well. To humans, the toxin causes nausea, vomiting, swelling, and severe pain, but should not be fatal. The crown-of-thorns starfish contains this toxin all the way from birth to adulthood.