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.
Italian crested newt
Development brings many changes about in the Italian crested newt. One of these is the alteration from oxyconformer to oxyregulator. Obviously, this difference will change how the newt deals with changes in its respiratory conditions. Another developmental change is the loss of external gills from juvenile stage to adulthood. This affects "T. carnifex" as the difference between being able to outreach the DBL (juvenile) and the inability to do this (adult). This inability introduces a diathesis to hypoxia in stagnant water. This is because there is a lack of convection in the water, and the oxygen is being subtracted more quickly than it can diffuse (due to oxygen’s slow diffusion constant through water).