A Federation species seen in Star Trek: The Motion Picture wearing full-face breathing masks fed from tanks on the back, since they cannot breathe an ordinary oxygen atmosphere.
The Zaranites are humanoids whose most obvious feature is their life support: a dark mask covering the face, with large goggle-like eyepieces and hoses running to a pack worn on the back. Beneath it they have grey, ridged skin. The equipment lets them work beside oxygen breathers aboard Starfleet ships and on Earth.
They appear in Star Trek: The Motion Picture, in the San Francisco air tram station and among the crew gathered on the recreation deck of the refitted Enterprise, where at least one wears a Starfleet uniform.
The species is never named on screen. The name comes from costume designer Robert Fletcher's notes for the film, which state that Zaranites breathe fluorine gas from their home world's atmosphere and so must carry a supply with them wherever they go.