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.
Smooth newt
Researchers cannot yet say how widely the species will spread because this is the first newt species found in the wild in Australia. However, smooth newts are prolific breeders and can survive in a wide range of terrestrial and aquatic habitats. Based on where they live in Europe – fields, woodlands, and a range of disturbed habitats, scientists suspect that they're capable of surviving in many areas of southern Australia. Furthermore, the climate of south-eastern Australia resembles the species’ native range, and climate matching suggests that large parts of NSW, Victoria, eastern Tasmania, southern South Australia, and south-western Western Australia are suitable for newt habitation.