von Cindy
in Blog
Zugriffe: 905

The Crown of Thorns: A Marine Enigma

Writing an article about Acanthaster planci, commonly known as the Crown of Thorns (COTs), requires addressing several key points, including what to do when you encounter them, what not to do, the concept of an outbreak, their ecological function, and their predators. Let's break down these aspects in our article below.


The Crown of Thorns (Acanthaster planci) is a marine creature that has fascinated and confounded scientists and marine enthusiasts for decades. This striking and often misunderstood echinoderm plays an integral role in the complex ecology of coral reefs. In this article, we will explore how to respond when encountering COTs, what not to do, the notion of COT outbreaks, their ecological functions, and their natural predators.

What to Do When You See COTs?

01. Report Sightings:

When you encounter COTs while snorkeling, diving, or exploring coral reefs, it's crucial to report your observations to local marine authorities or conservation organizations. Timely reporting can aid in monitoring and managing COT populations.

02. Safe Observation:

If you're a responsible and experienced diver, you can observe COTs from a safe distance. Avoid touching them as their spines can deliver a painful sting.

03. Participate in Removal Efforts:

Some conservation initiatives may organize COT removal programs, and you can participate to help mitigate their impact on coral reefs.

What Not to Do When You See COTs?

  1. Do Not Touch:

Never attempt to touch or handle COTs without proper training and protective gear. Their sharp spines can cause injury and deliver venomous stings.

02. Avoid Agitating Them:

Refrain from agitating or provoking COTs. Agitated individuals may release their toxic digestive enzymes, which can further damage the surrounding coral.

03. Do Not Relocate:

Resist the urge to move COTs from one location to another as this can disrupt their natural behavior and potentially spread them to new areas.

What Is an Outbreak of COTs?

An outbreak of COTs refers to a sudden and significant increase in their population, which can lead to substantial damage to coral reefs. These outbreaks can occur due to various factors, including environmental conditions, nutrient run-off, and changes in predator populations.

What Is Their Function?

COTs play a complex role in coral reef ecosystems:

  1. Natural Predation:

In healthy coral reef ecosystems, COTs act as natural predators of certain coral species, helping to maintain coral diversity and overall reef health.

02. Population Control:

They feed on the fastest-growing corals, preventing these species from overcrowding the reef and allowing slower-growing species to thrive.

What is their diet?

- Young COTs eat encrusting (coralline) algae, which are common on rocks and rubble on the reef.
- At about 6 months, they start to eat coral and begin to grow more rapidly.
- They spend about half of their active time feeding on coral polyps.
- They have a cryptic behavior: they tend to hide during the day and feed at night. However, during outbreaks they feed both during the day and at night.
- They alter coral community structure by preferentially feeding on certain species of hard corals (scleractinian corals).
- An individual starfish can consume up to 300 cm2 of living coral reef per year.

What Are Their Predators?

While COTs have few natural predators due to their venomous spines, some species do feed on them, helping to control their populations.

Predators of COT’s adult individuals:

  1. Humphead Wrasse (Cheilinus undulatus):

Certain species of wrasse, like the humphead wrasse, are known to feed on COTs.

02. Giant Triton Snail (Charonia tritonis):

The giant triton snail is another natural predator of COTs, helping to keep their populations in check.

03. Emperor fish (Lethrinus nebulosus)

04. Puffer fish (Arothron stellatus)

05. Triggerfish (Balistoides viridescens)

Predators of COT’s eggs and larvae:

  1. Planktivorous damselfish


In conclusion, the Crown of Thorns is a captivating but potentially problematic species in coral reef ecosystems. Proper response when encountering them, awareness of what not to do, understanding outbreaks, recognizing their ecological functions, and knowing their natural predators are all essential aspects of preserving the delicate balance of our oceans and protecting the world's coral reefs.

IMG 0343


Leave your comments


  • No comments found