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.
Ned's Newt
The series begins with Ned finally scraping up enough money to buy a pet. However, upon reaching the pet store, the only thing he can actually afford is a newt. Dubbing his new pet "Newton", Ned quickly tires of it, since Newton just lies on the rock in his bowl. Complaining to the pet store owner that his new pet is not very active, the owner gives Ned a can of "Zippo for Newt" pet food but warns Ned not to give his pet too much. Ned feeds Newton a little, but Newton does nothing. Ned leaves the can beside Newton's bowl and goes to bed.