Echinoderms
Crown-of-thorns starfish
Acanthaster planci
Epipelagic zone
Able to devour an entire coral reef within months during massive outbreaks, it is also one of the few starfish with genuinely venomous spines.
🗺️ Geographic range
Coral reefs of the Indo-Pacific, from the Red Sea to Australia's Great Barrier Reef.
📊 Population
Not threatened: the problem runs the other way — its periodic, massive outbreaks (several million individuals on a single reef) are one of the main causes of coral reef degradation in the Indo-Pacific.
Habitat
- Pacific Ocean · Coral reef · Epipelagic zone · Permanent
- Red Sea · Coral reef · Epipelagic zone · Permanent
🥚 Reproduction
External fertilisation; a single female can release several tens of millions of eggs.
Behaviour
- Diet
- Coral polyps, digested externally by covering the coral with its everted stomach.
- Hunting
- Moves slowly across the coral using hundreds of tube feet.
- Communication
- None.
- Social life
- Generally solitary, except during massive population outbreaks.
Physiology
- Anatomy
- A body covered in long venomous spines that can exceed several centimetres.
- Respiration
- Dermal gills spread across the body.
- Vision
- Rudimentary eyespots at the tip of each arm.
- Adaptations
- Regeneration ability: a severed arm, or even a partial central disc, can regrow into a whole individual.
🔗 Web of marine life
Predators
⚡ Its extraordinary abilities
- Can regenerate a whole individual from a fragment of its body
- Can devour an entire coral reef within months during a massive outbreak
🏆 Records
One of the few genuinely venomous starfish for humans
Its spines cause intense pain that can last several hours.
Source: Australian Museum
If you cross paths with this animal…
Risk: Moderate: its spines cause intense pain and can trigger nausea.
Behaviour: Not aggressive, dangerous only on direct contact.
Advice: Never touch with bare hands; wear thick gloves for any handling.
💡 Did you know?
- A single female can release several tens of millions of eggs in one season.
- Its massive outbreaks are one of the leading threats to the Great Barrier Reef.
