The Kaleds could be distinguished from Thals by their dark hair and eyes. (TV: Genesis of the Daleks) Internally, Kaleds also differed from both humans and Thals. Blood tests showed that humans and Gallifreyans were biologically very dissimilar to them. (TV: Genesis of the Daleks) Kaleds had purplish tissue and their ribs were more widely spaced than those of humans. (TV: The Stolen Earth) They had thicker lungs than the Thals and they had a copper-based blood which was greenish. The Kaled heart was grey. (AUDIO: Corruption)