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Sea Stars: Asteroidea

Crown-of-thorns (acanthaster Planci): Species Accounts

Physical characteristics: Crowns-of-thorns are about 16 inches (40 centimeters) across and have ten to thirty arms covered in thorn-like spines, which are venomous. These sea stars are red and green, and the spines have reddish tips. Young crowns-of-thorns have camouflage coloring.


Geographic range: Crowns-of-thorns live in the Pacific and Indian oceans.


Habitat: Adult crowns-of-thorns live on open sand and feed among coral. The young hide among the coral, under rocks, and in coral rubble.


Diet: Crowns-of-thorns are greedy predators of coral.


Behavior and reproduction: Crowns-of-thorns feed at night. Large swarms appear suddenly, feed on coral, and then disappear. These Crowns-of-thorns are greedy predators of coral. These sea stars turn their stomach inside out over coral, releasing an enzyme that turns the coral tissue to liquid, and then absorb the liquid. (Andrew J. Martinez/Photo Researchers, Inc.) sea stars turn their stomach inside out over coral, releasing an enzyme that turns the coral tissue to liquid, and then absorb the liquid. Crowns-of-thorns can survive without food for six months and feed on about 3 square miles (8 square kilometers) of coral per year. Crowns-of-thorns can regrow broken arms to form another star. These animals have separate sexes and reproduce by releasing eggs and sperm into the water, where fertilization takes place. There are two stages of larvae.


Crowns-of-thorns and people: Crowns-of-thorns have caused widespread damage to coral reefs. The stings of these sea stars are painful and cause nausea.


Conservation status: Crowns-of-thorns are not considered threatened or endangered. ∎

Additional topics

Animal Life ResourceJellyfish, Sponges, and Other Simple AnimalsSea Stars: Asteroidea - Physical Characteristics, Behavior And Reproduction, Sea Stars And People, Sand Star (astropecten Irregularis): Species Accounts - GEOGRAPHIC RANGE, HABITAT, DIET, CONSERVATION STATUS