Italian crested newt
When newts are inactive or in oxygen-rich environments, respiration can be done through their skin which accounts for 74% of the cutaneous respiration. However, oxygen-poor environments, such as stagnant ponds, pose a threat to the survival of larval newts. This is because oxygen molecules do not readily dissolve in water, and as "T. carnifex" is an immobile animal, extracting oxygen from water is difficult. Newts consequently have external gills at birth that persist until metamorphosis, which assists survival in low-oxygen conditions.
Black-spotted newt
Black-spotted newts prefer shallow-water habitats, heavy with vegetation. During the dry season, they are believed to burrow underground or remain under debris. They are carnivorous, consuming a wide variety of prey, including insects, aquatic invertebrates, leeches, and other amphibians. Their toxic skin secretions are used to deter predators. Breeding occurs year round. The life history of this species is not well known and the presence of an eft stage has yet to be determined.