Crown-of-thorns starfish outbreaks have wreaked havoc on the Great Barrier Reef’s several reefs since 1962. In the World Heritage Area, a fourth outbreak is now ongoing.
Crown-of-thorns starfish (also known as COTS) are coral-eating marine invertebrates. They’re found on reefs all around the Indo-Pacific, and when the conditions are right, they may spread like a plague, decimating hard coral communities.
After coral bleaching, crown-of-thorns starfish are a major driver of coral loss on the Great Barrier Reef, according to our research.
On the Reef, AIMS manages a large crown-of-thorns starfish monitoring program. Over a 15-year period, this long-term study found that epidemics start in the north and travel south, with ocean currents moving larvae between reefs.
The surveys also reveal that good reefs rebound after outbreaks, but it takes 10 to 20 years. However, reefs that are subjected to additional stresses, such as coral bleaching, cyclones, or poor water quality, take longer to recover, and the coral may not fully recover before the next round of breakouts.
Does the Crown-of-Thorns sea star eat anything other than coral?
Crown-of-thorns starfish (Acanthaster planci) are a type of corallivore (i.e., they feed coral polyps) that can be found on coral reefs. They come in a variety of colors, ranging from purplish blue to reddish-gray to green, and are covered in sharp venomous spines. They usually have a diameter of 25-35 cm, although they can get as big as 80 cm.
Crown-of-thorns starfish can be found all over the Indo-Pacific region, from the Red Sea and East African coasts to the Pacific and Indian Oceans and Central America’s west coast. The gigantic triton snail (Charonia tritonis), stars and stripes pufferfish (Arothron hispidus), titan triggerfish (Balistoides viridescens), and humphead maori wrasse are all predators of COTS (Cheilinus undulates).
Crown-of-thorns starfish eat almost all corals, and their feeding preferences and behavior patterns change depending on population density, water motion, and species composition.
What do crown-of-thorns starfish like to eat?
Crown-of-thorns The polyps of hard, rather fast-growing stony corals, such as staghorn corals, are generally eaten by starfish. They will devour other coral species if food is short. They eat by extruding their stomachs from their bodies and onto the coral reef, where they digest the coral polyps with enzymes. This procedure can take several hours to complete. The sea star departs when the coral polyps have been devoured, leaving only the white coral skeleton behind.
What is the main predator of crown-of-thorns starfish?
The gigantic triton snail, humphead Maori wrasse, starry puerfish, and titan trigger fish are all predators of adult crown-of-thorns starfish. Shrimp, crabs, and polychaete worms are all predators of immature starfish.
Do crown-of-thorns starfish eat phytoplankton?
Once established, juvenile crown-of-thorns starfish can reach adulthood in two years and produce a new outbreak if there are enough of them.
In the past, the first outbreaks were discovered between Cairns and Lizard Island (Wooldridge and Brodie 2015). They then slowly migrated down the coast over a 15-year span, until dissipating off the Mackay coast.
The outbreaks also occur on the reefs of far north Queensland, the Swains Reefs, the Capricorn-Bunkers, and the Torres Strait, but due to a paucity of surveys in these areas, nothing is known about the patterns of outbreaks. Although no outbreaks are known to occur on the coral reefs of the Coral Sea, no regular surveys have been done.
What do crown-of-thorns starfish look like?
The crown-of-thorns starfish (Acanthaster planci) has a central disk from which its arms emerge, similar to other starfish. They have many soft arms (more than the usual five) that are covered in spines, which distinguishes them from other creatures. Their arms are also prehensile, allowing them to grasp objects. Crown-of-thorns starfish can grow up to 10-14 in (25-35 cm) in length and have more than 20 limbs when fully grown. They’re also available in a range of colors, including bluish-purple, red, gray, and green.
How cute are they?
The COTS (a coral predator) is more interesting and appealing than cute. Their brilliant colors, such as purple, gray, and green, as well as their spiky body, are fascinating to observe.
How do they communicate?
The method these organisms communicate is mostly unknown. A recent study, however, may give some illumination, as it was discovered that they communicate with one another through chemical release. COTS from different places, such as COTS from the Indo-Pacific region (which are a coral reef pest) and COTS from Japan, have been found to release the same compounds. When they are attacked by a predator, they appear to emit various proteins, but there is still a lot more to discover about these fascinating aquatic critters.
How big is a crown-of-thorns starfish?
The average adult crown-of-thorns starfish is 10-14 inches long (25-35 cm). The long and pointed spines on the sides of the starfish’s arms and upper (aboral) surface resemble thistles, and can have up to 23 arms. They resemble a crown, which gives the animal its name. The spines are solid, pointed, and may easily puncture through fragile surfaces, growing up to 0.13 ft (4 cm) long.
How did it get its name?
The venomous thorn-like spines that cover the upper surface of the crown-of-thorns starfish (coral reef eater) give it its name. These resemble the biblical crown of thorns in appearance.
Would they make a good pet?
They cannot be kept as pets because they dwell in the waters and contribute to the balance of their ecosystems. Crown-of-thorns starfish are predators that eat a variety of corals. They can only live in the deepest parts of the ocean, where they may feed on vast amounts of corals.
Kidadl Recommendation: Only purchase pets from a reliable provider. It is important that you conduct your own research as a potential pet owner before deciding on your pet of choice. Being a pet owner is extremely rewarding, but it also necessitates a significant amount of time, effort, and money. Check to see if the pet you’ve chosen is legal in your state and/or nation. You must never capture wild animals or harm their habitat. Please double-check that the pet you’re thinking about buying isn’t an endangered species, isn’t on the CITES list, and hasn’t been captured in the wild for the pet trade.
Did you know…
One of the most interesting crown-of-thorns starfish facts for kids is that they feed on their prey, coral reef, by ejecting their stomachs from their bodies and covering the corals!
Crown-of-thorns starfish are nocturnal and can eat 53.8-140 square feet (5-13 square meters) of coral in a single year. COTS are the primary cause of reef damage in Australia’s Great Barrier Reef.
The poison of the crown-of-thorns starfish contains saponin, a chemical component that is deadly to both humans and fish. The sting of a crown-of-thorns starfish can produce numbness, tingling, nausea, and agony across the body.
On the Great Barrier Reef, AIMS has a large COTS checking operation. This long-term study found that epidemics start in the north and move south over 15 years, with the ocean transporting larvae between reefs.
Why is the crown-of-thorns starfish a problem?
Coral-eating crown-of-thorns starfish can be an issue. Under extreme circumstances, this sea star can have outbreaks that cause huge coral reef devastation, threatening the vital coral cover. Coral reefs are crucial for many undersea animals, and they also help to reduce the intensity of the waves that pound our coasts.
Can a crown-of-thorns starfish kill a human?
Although the venom of crown-of-thorns starfish (coral reef eater fish) cannot kill humans, their spines do contain neurotoxic and starfish poison, which is harmful to both humans and marine life.
We’ve painstakingly crafted a variety of interesting family-friendly animal facts for you to explore at Kidadl! Learn more about the ground beetle and the American dagger moth, two more arthropods.
You can even color one of our crown-of-thorns starfish coloring sheets at home to keep yourself occupied.
How do you control a crown-of-thorns starfish?
As part of the Marine Park Authority’s Crown-of-thorns Starfish Strategic Management Framework, the Crown-of-thorns Starfish Control Program was formed in 2012 and provides a tactical reaction to outbreaks.
The method employs dedicated vessels with highly trained crews to hand cull starfish using bile salts or household vinegar as a deadly injection. The Crown-of-thorns Starfish Control Program also includes strategic surveillance and monitoring efforts. This ensures that culling efforts are focused on the areas that will provide the most benefit, that progress is tracked, and that pest control outcomes are maintained once they have been reached.
Supporting the environment and Reef communities
The Crown-of-thorns Starfish Control Program provides social and economic benefits to Australians in addition to environmental benefits for the Great Barrier Reef’s health. The program has been delivered in collaboration with the Reef tourism industry through the Association of Marine Park Tourism Operators since its inception (AMPTO). The reef is kept healthy in areas where local tourism firms send their national and international customers to experience the Great Barrier Reef through targeted crown-of-thorns starfish control. More than 100 people, mostly from Queensland, are trained and employed as part of the initiative.
Program growth and funding
At first, the program only had one or two dedicated ships. However, the outbreak that started in the northern management region in 2010 migrated south over time. The Crown-of-thorns Starfish Control Program received more money in 2018. In 2018-19, the program was able to expand from two to six vessels thanks to the additional funding. The expansion of the program allowed for the first time the deployment of crown-of-thorns starfish control vessels in the Marine Park’s far north and far south.
Five crown-of-thorns starfish control vessels have been deployed in the Marine Park’s northern, central, and southern management districts as of 2019-20. Control activities are deliberately tailored within each management region to focus on reefs of high ecological and economic value.
Since 2012, the Australian government has been funding the Crown-of-thorns Starfish Control Program. The Reef Trust Partnership (RTP) between the Great Barrier Reef Foundation (GBRF) and the Department of Agriculture, Water and the Environment provided funding for the Program in 2019-20. (DAWE). The GBRF and the DAWE have fully supported it through the RTP for 2020-22. The GBRF, the Great Barrier Reef Marine Park Authority (the Marine Park Authority), and the Reef and Rainforest Research Centre have formed a strategic collaboration to deliver the Program’s manual in-water control component (RRRC).
Are crown of thorns invasive?
- Purple sea urchins (Strongylocentortus purpuratus) are native to the United States’ Pacific Coast. Natural predators of the purple sea urchin, such as sea otters and sea stars, have declined in numbers (Pearse 2006). The resulting population explosion of purple sea urchins has ravaged kelp forests, which are important homes for many marine animals (Pearse 2006).
- Europe and North Africa are home to the European Green Crab (Carcinus maenas). The crab, which is found in the Americas, Australia, and South Africa, preys on a wide range of creatures but is especially damaging to bivalves (Colnar & Landis 2007).
How long do crown-of-thorns starfish live?
Although the wild life expectancy of crown-of-thorns starfish is unknown, they do age and reach the senile stage after 3-4 years. The majority of the specimens tested perished between the ages of 5 and 7.5 years. They can live for 8 to 15 years in captivity.
Are starfish poisonous?
No, starfish are not dangerous, and their spikes cannot harm you unless they pierce your skin or if the spike contains a venomous substance, which only occurs in a few species of sea stars, such as urchins.
Experts advise against picking up starfish, especially if they’re on the beach. Regardless matter how lovely they are, they are crucial members of ocean ecosystems and should be allowed alone to thrive.
What about urchins? Are they dangerous?
If handled incorrectly or without gloves, urchins can be extremely dangerous, as their poisonous spikes can cause significant harm.
Sea urchins pierce the skin, leaving puncture wounds that can become septic. Within moments of touch, the affected area becomes red, swollen, and painful.