The Crown-of-Thorns Starfish
The crown-of-thorns starfish (Acanthaster planci), so named because of the spines that cover the upper surface of its body, is an integral part of coral ecosystems. These starfish help ensure the diversity of coral reefs by feeding predominantly on fast-growing corals, thereby creating space for slower-growing types that would otherwise be drowned out. When they multiply beyond their usual numbers, however, they can consume entire populations of reef-building corals and severely disrupt the natural balance. Crown-of-thorns starfish are regularly culled in the sea off Tosashimizu to keep the population in check and maintain the stability of the marine ecosystem.