“The sea star moves with a slow, deliberate grace across the reef — a five-armed predator whose beauty belies its effectiveness as a hunter.”
Sea Stars (Starfish) of the Great Barrier Reef – From Predators to Reef Cleaners
Explore Great Barrier Reef Invertebrates
Sea stars, commonly known as starfish, are among the most fascinating reef invertebrates found on the Great Barrier Reef. With their colourful patterns, incredible ability to regenerate limbs, and slow graceful movements across coral reefs and sandy lagoons, sea stars are an important part of the reef ecosystem and a favourite marine animal for snorkellers and divers.
The Great Barrier Reef is home to many different species of sea stars, from tiny reef stars hiding among coral to the famous blue sea star and the large crown-of-thorns starfish.
Quick Facts
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- Sea stars are not fish — they are marine invertebrates
- They are echinoderms, a group (phylum) that also includes sea urchins and sea cucumbers
- Most sea stars have five arms, although some species have many more
- They move using hundreds of tiny tube feet
- Sea stars can regenerate lost arms
- Some species feed on coral, algae, or small animals
- The Great Barrier Reef is home to dozens of sea star species
Sea Star Taxonomy
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- Kingdom: Animalia
- Phylum: Echinodermata
- Class: Asteroidea
- Order: Valvatida (all the families listed below)
Common Great Barrier Reef Sea Star Families
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- Oreasteridae – Cushion stars and large reef sea stars
- Acanthasteridae – Crown-of-thorns starfish
- Ophidiasteridae – Blue sea star (Linckia) and related reef stars
- Goniasteridae – Decorative reef sea stars
What Do Sea Stars Look Like?
They are instantly recognisable for their star-shaped bodies and radiating arms. While many species have five arms, others can have 10, 20, or even more.
They come in a wide range of colours and textures including:
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- Bright blue
- Orange
- Red
- Purple
- Brown
- Spotted or patterned designs
Some species have smooth skin, while others feature spines, bumps, or armoured plates for protection.
Popular Great Barrier Reef species include:
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- Blue Sea Star
- Cushion Star
- Granulated Sea Star
- Horned Sea Star
- Crown-of-Thorns Starfish
Where Are Sea Stars Found on the Great Barrier Reef?
Sea stars can be found throughout the Great Barrier Reef Marine Park in a variety of habitats including:
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- Coral reefs
- Reef flats
- Sandy lagoons
- Seagrass beds
- Tidal pools
- Island beaches
Visitors often spot sea stars around:
How Do Sea Stars Move?
Sea stars move using hundreds of tiny tube feet located underneath their arms. These feet operate through a unique water vascular system that helps them grip surfaces and slowly glide across the reef.
Although they appear slow, sea stars are surprisingly effective hunters and scavengers.
What Do Sea Stars Eat?
Depending on the species, sea stars may feed on:
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- Algae
- Coral polyps
- Molluscs
- Sponges
- Tiny reef animals
- Organic matter on the seabed
Some species, like the crown-of-thorns starfish, feed primarily on hard coral and can impact reef health when populations grow too large.
Crown-of-Thorns Starfish
One of the most well-known sea stars on the Great Barrier Reef is the crown-of-thorns starfish.
This large sea star, up to about 80 cm across, is covered in toxic spines up to 4 cm long and feeds on live hard coral. While crown-of-thorns starfish are native to the reef and naturally part of the ecosystem, population outbreaks can damage coral reefs if numbers become excessive.
The Great Barrier Reef Marine Park Authority runs a crown-of-thorns control program, and surveys by the Australian Institute of Marine Science help find reefs where numbers are building up.
Can Sea Stars Regrow Arms?
One of the most remarkable features of sea stars is their ability to regenerate lost arms. Most sea stars need part of the central disc to regrow, but a few, including some blue sea stars (Linckia), can regrow a whole new animal from a single arm.
This incredible survival ability helps sea stars recover from predator attacks and injuries.
Are Sea Stars Dangerous?
Most sea stars are completely harmless to humans and should simply be admired underwater.
However:
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- Crown-of-thorns starfish have toxic spines that can cause very painful injuries
- Sea stars should never be removed from the water
- Handling sea stars can damage their delicate skin and internal systems
Visitors should always observe marine life respectfully and avoid touching reef creatures. If someone is spiked by a crown-of-thorns starfish, St John Ambulance first aid advice is to call 000, carefully remove any visible spines, clean the wound and place the area in hot water no hotter than the first aider can comfortably tolerate.
Best Ways to See Sea Stars on the Great Barrier Reef
They are commonly seen during:
Shallow coral lagoons and sandy reef flats are often the best places to spot colourful sea stars resting among coral rubble or seagrass.
Sea Stars Recorded on the Great Barrier Reef
- Blue Sea Star (Linckia laevigata) – family Ophidiasteridae
- Crown-of-Thorns Starfish (Acanthaster cf. solaris) – family Acanthasteridae
- Granulated Sea Star (Choriaster granulatus) – family Oreasteridae
- Horned or Chocolate Chip Sea Star (Protoreaster nodosus) – family Oreasteridae
- Nardoa tuberculata – family Ophidiasteridae
- Sand Sea Star (Archaster typicus) – family Archasteridae
Role on the Reef
Most sea stars are scavengers and grazers that help recycle detritus and the thin film of algae on reef surfaces. The crown-of-thorns starfish is the exception: each adult can eat up to about 10 square metres of hard coral a year, and during outbreaks it can kill most of the coral on affected reefs, which is why it is closely managed (Australian Institute of Marine Science).
Learning about reef animals in class? We help schools, universities and study groups plan educational trips to the Great Barrier Reef. Depending on the program, groups can enjoy guided snorkelling and marine biology presentations.
Great Barrier Reef Educational Groups →
Frequently Asked Questions About Sea Stars
Are sea stars fish?
Can sea stars regrow arms?
What is the most famous sea star on the Great Barrier Reef?
Is it safe to touch sea stars?
Where can I see sea stars on the Great Barrier Reef?
Discover More Great Barrier Reef Invertebrates
The Great Barrier Reef is home to an extraordinary range of marine invertebrates including giant clams, sea cucumbers, nudibranchs, octopus, reef crabs, and colourful sea stars.
Whether you are snorkelling shallow coral gardens or exploring the reef on a dive adventure, spotting a beautiful sea star resting quietly on the reef is one of the many magical moments visitors remember long after leaving the Great Barrier Reef.
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