Space Pirates, or Zebesians, serve as the antagonists of the Metroid series. They are a group of "interstellar nomads" resembling humanoid reptiles, insects or crustaceans, who plunder colonies and ships and exist in an insect-like hive society. Considering their appearannce throughout the series, especially the Prime series, they could be considered arthropodian-like reptiles. A single Pirate may have many biological differences between individuals of their own species, most likely because of their willingness to perform self-experimentation and mutation. Important leaders include Ridley, the Space Pirate commander, Mother Brain, the biomechanical defense of Zebes controlled by the Space Pirates, and Kraid, a recurring boss. The organization also includes a winged, mantis-like species, the Ki Hunters. The Space Pirates are interested in Metroid research, especially in using Metroids for energy generation, as soldiers, and for experimentation – their Phazon experiments produced all the Metroid variants seen in the Prime games with the exception of Metroid Prime itself. The organization is destroyed during the climax of Super Metroid, however a group within the Galactic Federation itself resurrects the Space Pirates, along with Ridley and the Metroids, to be used as bio-weapons explaining their continued presence in Other M and Fusion.