Newt
Newts, as with salamanders in general and other amphibians, serve as bioindicators because of their thin, sensitive skin and evidence of their presence (or absence) can serve as an indicator of the health of the environment. Most species are highly sensitive to subtle changes in the pH level of the streams and lakes where they live. Because their skin is permeable to water, they absorb oxygen and other substances they need through their skin. Scientists study the stability of the amphibian population when studying the water quality of a particular body of water.
Fire belly newts
The fire belly newts or fire newts are a genus (Cynops) of newts native to Japan and China. All of the species show bright yellow or red bellies, but this feature is not unique to this genus. Their skin contains a toxin that can be harmful if ingested.The genus "Cynops" has been suggested to be due for a split, with the Chinese species being placed in a separate genus from the Japanese ones. The species "Cynops cyanurus" is at the centre of all this. There is much debate about the validity of "C. cyanurus" and "C. chenggongensis". All the known captive animals could be something different from "C. cyanurus", as they do not entirely match the original description of the species. The only known animals that match that are animals originating from Chemnitz Zoo, but the F2 animals have not bred well, which could suggest they are in fact a hybrid of "C. cyanurus" and "C. chenggongensis" or an undescribed "Cynops" species.