Amphibian

An amphibian was an animal that could live on land or in water.

Amphibious species encountered by the Doctor included the Aridians, (TV: The Chase) the Mentors (TV: Vengeance on Varos, Mindwarp) and the Staggs. (PROSE: Terror on Tiro) Amphibious individuals he met were Destrii (COMIC: Ophidius, Oblivion) and Thiss. (PROSE: The Serpent's Tooth)

The Institute had a hothouse wing for amphibians. (AUDIO: Unregenerate!)