Conventional biology is grounded in matter-bound environments such as liquid water, atmospheric gases, and solid substrates. Planetary systems are embedded in extended electromagnetic plasma structures that form stable cavities, ducts, and resonant regions within ionospheric and magnetospheric fields. These field-defined habitats differ fundamentally from neutral-gas or liquid environments, exhibiting low-collision dynamics, high coherence, and phase-stabilized energy transport. This paper establishes a framework for coherent plasma biology: a class of life adapted to structured electromagnetic and plasma environments rather than planetary surfaces. Plasma physics, neurophysiology, bioelectromagnetics, and thermodynamics converge to show that organisms in such habitats naturally develop nervous systems based on resonance, impedance matching, and phase coherence rather than chemical diffusion. Hybrid carbon–mineral–ionic architectures emerge as the most thermodynamically stable configuration for sustained life in field-dominated environments. Longevity, entropy control, and biosignature detection in non-surface habitats are examined. coherent biology, plasma life, bioelectromagnetics, ionosphere, magnetosphere, field-defined habitats, resonance biology, silicon-hybrid life, electromagnetic nervous systems, plasma ecology, astrobiology, coherence physics, entropy control

coherent biology, plasma life, bioelectromagnetics, ionosphere, magnetosphere, field-defined habitats, resonance biology, silicon-hybrid life, electromagnetic nervous systems, plasma ecology, astrobiology, coherence physics, entropy control