One starfish can strip a reef bare, and cutting it apart only makes more of it
The crown-of-thorns starfish, covered in venomous spines, feeds by climbing onto living coral and extruding its stomach onto the surface to digest the tissue in place, and a single outbreak can devastate acres of reef. Early efforts to control outbreaks by hacking the starfish apart backfired, since many fragments simply regenerated into new, complete starfish. Divers now inject individual starfish with substances like bile salts, which kill them without multiplying the population instead.