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
Temperature plays a key role in the osmoregulation of the newt. Not only do the changing seasons drive "T. carnifex" either into the water or onto land, it also regulates the release of certain hormones in accordance with the osmotic permeability of the newts' epidermis. Osmotic permeability is dependent on the release of hormones such as prolactin, vasotocin, as well as other thyroidal and internal hormones. Brown et al. experimented on a close relative of "T. carnifex" to determine the effects different environmental conditions have on the newts osmoregulatory systems.