1. Natural larval dispersal: The Crown of Thorns Starfish is native to the Indo-Pacific region, and it is believed that the starfish may have arrived in Australia through natural larval dispersal. Crown of Thorns Starfish larvae can travel long distances in ocean currents, and they can settle and grow in new areas if conditions are suitable.
2. Human introduction: It is also possible that the Crown of Thorns Starfish was introduced to Australia by humans, either intentionally or unintentionally. The Crown of Thorns Starfish is a valuable food source in some cultures, and it is possible that people brought the starfish to Australia for food or for the aquarium trade. Additionally, the Crown of Thorns Starfish can attach to ships and other marine vessels, and it is possible that the starfish was accidentally transported to Australia in this way.
Regardless of how the Crown of Thorns Starfish arrived in Australia, it is now a well-established species in the region. The starfish has caused significant damage to coral reefs along the Great Barrier Reef and other areas of the Indo-Pacific region, and it is considered a major threat to marine ecosystems.