The Crown-of-thorns Starfish, scientifically known as Acanthaster benziei, is a large and distinctive starfish species characterized by its spiky, venomous body. It is a prominent inhabitant of coral reefs, and its impact on these delicate ecosystems has been the subject of much scientific study. This article delves into the biology, behavior, and ecological role of this fascinating and sometimes controversial creature.
Description & Characteristics
Acanthaster benziei is easily recognized by its bright, often vibrant, coloration, which can range from red to orange, yellow, or even purple. Its body is covered in numerous long, sharp spines, giving it a formidable appearance. These spines are venomous, and a sting can be painful and potentially dangerous to humans. The starfish can grow up to 35 cm in diameter, making it one of the largest starfish species. It has a distinctive, star-shaped body with five arms that radiate outwards from a central disc.
Habitat and Occurrence
Acanthaster benziei is primarily found in the tropical waters of the Indo-Pacific region. It is a common inhabitant of coral reefs, where it can be found in various depths, from the shallows to the deeper parts of the reef. Its habitat preferences include rock crevices, underwater caves, and underwater caverns. The species is typically found in the subtidal, sublittoral, and infralittoral zones, which extend from the lower limit of the intertidal zone to the shelf edge at about 200 m water depth. This makes it a resident of the neritic zone, the marine environment extending from the coastline out to the edge of the continental shelf.
Taxonomy
Acanthaster benziei belongs to the Class: Asteroidea, Order: Valvatida, and Family: Acanthasteridae. This family includes several other species of starfish, all of which share similar characteristics like the presence of venomous spines.
Feeding
Acanthaster benziei is a voracious predator that specializes in feeding on coral polyps. This makes it a corallivorous species, and its feeding habits can have a significant impact on coral reef ecosystems. It feeds by extending its stomach over the coral and digesting the polyps. It is estimated that a single Acanthaster benziei can consume up to 6 square meters of coral per year. This can result in extensive coral bleaching and damage, particularly when populations of the starfish become unusually large.
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