Wankhs are large amphibious roughly humanoid figures who have developed an interstellar civilisation. They are larger than humans with a massive and imposing torso, short legs and long arms with webbed hands and feet. Their morphology, streamlined for swimming, makes it impossible for them to sit. Their head is small and squarish with black lense like eyes that beat at regular intervals. At the base of their skull is a sonic organ with which they emit harmonics through which communicate. They have a scripture based on rectangular ideograms of different sizes which represent different harmonics and, apart from high dignitaries who may have golden leggings and medallion on the,, they do not wear any clothes or apparatus on their body.
The only recoreded contact of Wankhs with mankind is on planet Tschai where they established an outpost of strategic importance in their war against the Dirdir. That war, which started over ten thousands years ago has come to a stalemate following the Tschai truce. On Tschai, Wankhs also use some of the humans that were brought by the Dirdir that they have trained as servants.
Source : Planet of Adventure – The Wankh (Jack Vance)