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.
Danube crested newt
Both in water and on land, the newts are largely nocturnal. In their aquatic habitats, they hide under vegetation, and on land, they use structures such as logs, rocks, or small animal burrows for cover. They feed mainly on different invertebrates, but in the water may also prey on tadpoles and smaller newts. Predators include herons and other birds, snakes such as the grass snake, and various carnivorous mammals.