# Crown-of-thorns Starfish (*Acanthaster planci*)

> The crown-of-thorns starfish (Acanthaster planci) is a venomous coral predator whose outbreaks can devastate Indo-Pacific reefs. Adults reach 80 cm and are listed Least Concern.

- **Category:** Invertebrate
- **Conservation status (IUCN):** Least Concern
- **Range:** Indo-Pacific coral reefs.
- **Canonical page:** https://globalanimalguide.org/animals/crown-of-thorns/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Echinodermata
- **Class:** Asteroidea
- **Order:** Valvatida
- **Family:** Acanthasteridae
- **Genus:** Acanthaster

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Acanthaster planci |
| Diet | Carnivore (coral polyps) |
| Habitat | Coral reefs |
| Lifespan | 5–8 years |
| Weight | 2–5 kg |
| Top speed | up to 3 km/h |
| Conservation status | Least Concern (IUCN) |

## Spiny coral predator

Up to 21 arms bear venomous thorns. A stomach can be everted to digest coral polyps externally, leaving white scars on living reef.

## Coral polyp digester

A single adult can consume several square metres of coral yearly. Outbreaks of thousands per reef trigger mass bleaching-like damage.

## Indo-Pacific coral reefs

From the Red Sea and East Africa to the Pacific islands and Great Barrier Reef. Larvae ride currents for weeks before settling.

## Outbreaks, not extinction

IUCN lists the species Least Concern. Natural cycles and nutrient runoff drive outbreaks; divers manually remove stars and breeding disruption programs protect tourism reefs.

## Frequently asked questions

### Are crown-of-thorns starfish venomous?

Sharp spines deliver painful toxins — gloves are essential when handling them.

### Why are outbreaks a problem?

Thousands of stars can eat live coral faster than reefs recover, causing long-term damage.

### What causes crown-of-thorns outbreaks?

Nutrient runoff boosting plankton food for larvae and removal of natural predators may both play roles.

### How do crown-of-thorns eat coral?

They extrude their stomach onto polyps and digest tissue externally.

### Is the crown-of-thorns starfish endangered?

No — IUCN lists it Least Concern despite its threat to corals during outbreaks.

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Source: Global Animal Guide (https://globalanimalguide.org/animals/crown-of-thorns/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.