Acanthaster
Acanthaster is a genus of large, predatory sea stars, commonly known as crown-of-thorns starfish. These starfish are characterized by their distinctive spiny, often brightly colored bodies, which can reach up to 35 centimeters (14 inches) in diameter. Acanthaster species are found in the Indo-Pacific region, ranging from the Red Sea and the east coast of Africa to the eastern Pacific Ocean, including the Great Barrier Reef and the Hawaiian Islands.
Common Names
The most common name for Acanthaster species is "crown-of-thorns starfish," a name derived from the numerous, sharp spines that cover their bodies. Other names include "crown-of-thorns," "thorny starfish," and "spiny starfish."
Characteristics
Acanthaster starfish are easily recognizable by their numerous, sharp spines. These spines, which can be up to 3 centimeters (1.2 inches) long, are venomous and can inflict painful, sometimes serious wounds. The body of a crown-of-thorns starfish can vary in color, but it is usually a reddish-brown, purplish, or greenish-brown with white or yellow tips on its spines. Unlike other starfish, Acanthaster species possess a smooth, flexible body. Their arms, which typically number between 13 and 23, are thick and robust, allowing them to move rapidly and efficiently.
Environment
Crown-of-thorns starfish prefer to live in shallow, tropical waters, often found on coral reefs. They are nocturnal animals, hiding in crevices during the day and emerging at night to feed. Acanthaster species are carnivorous, feeding primarily on coral polyps. The starfish's diet can have significant impacts on coral reef ecosystems, as they can decimate entire coral colonies if their populations become excessive.