Newt
During the subsequent few months, the larvae undergo metamorphosis, during which they develop legs, and the gills are absorbed and replaced by air-breathing lungs. Some species, such as the North American newts, also become more brightly coloured during this phase. Once fully metamorphosised, they leave the water and live a terrestrial life, when they are known as "efts". Only when the eft reaches adulthood will the North American species return to live in water, rarely venturing back onto the land. Conversely, most European species live their adult lives on land and only visit water to breed.
Italian crested newt
"T. carnifex" is a member of a large family who all share common traits, one of which is the ability of this organism’s spleen to store large volumes of erythrocyte when the oxygen available goes beyond what is needed. Conversely, when the oxygen supply dips below necessary, the spleen of "T. carnifex" will release the red blood cells into the blood stream (as in cases of hypoxia, see below). This process will affect many aspects of the system, including the composition and volume of the blood. The surroundings of the animal will affect it. These surroundings include both the environment, and the physiological conditions the newt finds itself in. One such instance of this regulation is known as compensatory respiration, found during hypoxia. Hypoxia happens when there is an extremely low or limited amount of oxygen available to an organism.