Takaran

The Takarans are a humanoid species native to the planet Takara.The Takarans developed an extremely redundant internal physiology, which could indicate that the planet's environment is extremely inhospitable to most forms of humanoid life. (TNG: "Suspicions")

Takarans are characterized by a very unusual anatomy and physiology where their internal organs are not as distinct as those of most humanoids – their organ systems are much more evenly distributed around their bodies, resulting in Takarans having a very high resistance to injury. Takarans also have voluntary control over their own physiology down to a cellular level and can place themselves in a form of stasis resembling death.

To Starfleet medical equipment, only the rate of cellular decay could verify whether a Takaran was dead or alive – a slow rate of cellular decay was indicative of a Takaran in voluntary stasis; the rate of cellular decay would be much faster if the Takaran were truly dead – this was unknown to Doctor Beverly Crusher until 2369.

Takarans are also able to put only a part of their body in stasis at a time, enabling them to slow injury in specific areas and thereby reduce the overall effects of the injury. (TNG: "Suspicions")

Since Dr. Crusher knew little of Takaran physiology and also stated Jo'Bril was the first Takaran she'd ever met, it is unlikely that Takarans were Federation members as of 2369.