Sector 1 (Biosphere)
The Biosphere, also known as Sector 1, is a simulated-environment sector of the Bottle Ship and is the first such sector Samus Aran explores. Like the other simulated-environment sectors, the Cryosphere and the Pyrosphere, the Biosphere's environment is interspersed with mechanical rooms and structures. It, also like them, is housed in a dome-shaped area and is divided into four blocks. A lush, jungle environment, it is home to many varieties of flora and fauna and has an abundant supply of water, thanks to waterfalls and frequent bouts of rain. Vines choke certain corridors, and one room even contains a massive tree that is covered with large, interlocking vines and serves as the basis for a spiraling ramp. It is unique among the Bottle Ship's sectors in that its environment can be switched on and off via terminals scattered throughout, a feature that is necessary to reach certain areas.
It is a much more hostile sector compared to the Main Sector, as its primary residents are Kihunters, Ghalmanians, and Griptians, among others. However, its most notable resident is Little Birdie, a bird-like creature whose roar drives other creatures into a frenzy, encountered some time after its escape from the Breeding Room, in which is the mutilated corpse of its keeper. The sector also houses the Exam Center and the entrance to the Bioweapon Research Center. The last area Samus explores during her first visit to the sector, the Exam Center is fairly large and possesses a large quantity of computers and other technological equipment. It also contains one of the Bottle Ship's few non-organic threats: cyborg Zebesians. It is also significant as the last place in which Samus and the Galactic Federation 07th Platoon congregate.
The Biosphere is also the setting for a number of notable and bizarre events. After Samus and the platoon are interrupted in the Exam Center by the roar of an unidentified organism, the Exam Center is detonated via unknown means. The aforementioned organism, a lizard-like monstrosity, assaults Samus upon her exit from the facility, pinning her to the ground. The mutilated corpse of 07th Platoon member Lyle Smithsonian is found near the broken husk of Little Birdie, covered in green blood. During a later visit, Samus pursues the Deleter, an assassin clad in a Galactic Federation uniform, through the sector and the adjoining Bioweapon Research Center. Finally, Samus engages the persistent Rhedogian a final time in this sector, gaining the Seeker Missile upon its defeat. As in other sectors, Desbrachians appear in the Biosphere once Power Bombs are obtained.
- "The first such atmosphere is BIOSPHERE, designed to sustain organisms from warm and humid habitats. The structure of each sector is centered primarily on a cavernous dome. In order to maintain the structural integrity of the whole within the limits of material strength, each dome structure is divided into 4 blocks, for a total of 12." —Exam Center computer (Metroid: Other M)
- "The large, cagelike booth looked like something had been raised in it, and in one corner was the miserable form of a researcher's corpse. This victim hadn't sustained the same injuries; the dead I'd seen had been torn apart by something large. This one had been attacked by a different type of creature. And as I studied the violence this creature had wrought, I felt something in the air—the presence of a dark intelligence." —Samus Aran (Metroid: Other M)
- "Adam, are you seeing this? It's a Zebesian...but it's been cybernetically enhanced." —Samus Aran (Metroid: Other M)
- "Lyle's down! He looks like a pile of rags... What's gotta happen to a guy to make him look like that?!" —James Pierce (Metroid: Other M)