The Pirate Alarm System is a system of devices used by the Space Pirates on the Pirate Homeworld. It activates when intruders are detected. When activated, small antenna protrude from devices on the wall, flashing as they warn and summon Space Pirates to terminate the intruder. They are activated either by tripping laser devices or from small handheld alarms. Once the antennas are activated, Samus has a few seconds to shoot them until she runs out of time and is attacked by Space Pirates.
In the Metroid Manga, a device similar to the alarm system was used on Jigrad to measure the height of Jigrad children that were to become Space Pirate slaves. Those who were too short would not activate the device, and they would then be terminated. Samus and fellow Federation Police members interfered while it was in use, saving the lives of Damara and several other children. Later, Kreatz contemplated on selling it. Consisting of two portions, typically a pair of towers, it fires a beam that connects them. This beam causes no damage.
In Metroid Prime 3: Corruption, this device was also found on the Space Pirate Homeworld. Apparently upgraded, it now produced a beam that was invisible to all but the X-Ray Visor. Serving a similar purpose, it was now part of the Pirate Alarm System and would alert nearby forces (especially Pirate Commandos) whenever Samus passed through it. Samus could avoid it by going into Morph Ball mode and moving beneath it. Sometimes, when Samus was sighted, Space Pirates would run in and activate a beacon that sent a distress signal.
In Metroid: Zero Mission, a similar system was used on the Space Pirate Mother Ship and on the excavated ruins in Chozodia, and produced a visible green beam that if passed through would set off the ship's alarm system and alert the Space Pirates. Searchlights and floating-eye sensors were also used. The latter of which projects the alert beam while firing projectiles as an offensive.
- It is interesting to note that this device actually originally appeared in the Metroid Manga, and then made an appearance in a game.
- The sound effect of the Pirate Alarm siren was reused from Metroid Prime 2: Echoes, where it could be heard in the final report cutscene when the Dark Splinters attacked.