Fauna of Scotland
Only six amphibians and four land reptiles are native to Scotland. The amphibians include three species of newt: the great crested, of which fewer than 1,000 individuals survive; the smooth, and the palmate. The other amphibians are the common toad, the natterjack toad, found in only four locations in the south-west, and the common frog. A single alien amphibian is known in Scotland, the Alpine newt, a recent escapee confined to the Edinburgh area.
Newt
Newts share many of the characteristics of their salamander kin, Caudata, including semipermeable glandular skin, four equal-sized limbs, and a distinct tail. The newt's skin, however, is not as smooth as that of other salamanders. Aquatic larvae have true teeth on both upper and lower jaws, and external gills. They have the ability to regenerate limbs, eyes, spinal cords, hearts, intestines, and upper and lower jaws. The Japanese fire belly newt can regenerate its eye lens 18 times over a period of 16 years and retain its structural and functional properties. The cells at the site of the injury have the ability to undifferentiate, reproduce rapidly, and differentiate again to create a new limb or organ. One hypothesis is that the undifferentiated cells are related to tumour cells, since chemicals that produce tumours in other animals will produce additional limbs in newts.