Biodiversity

	Amphibians	amphibians
	Amphibians are unusual animals occurring throughout the world (except the two Poles). They can live and breathe both on land and in water (their name "amphibian" comes from the Greek word meaning both). However, they must return to water to breed.
	They lay eggs in water which hatch into tadpoles with gills, which in turn develop into air-breathing miniature replicas of their parents (metamorphosis). Their lungs are weak and they use their skins for oxygen exchange, enabling them to remain underwater for long periods. They are often considered as a freshwater group, even though they spend the majority of their lives on land.
	Their larvae are taken by many freshwater predators and the newly metamorphosed young also fall prey to terrestrial predators. So they breed in large numbers to cope with the high predation levels. They are cold-blooded, spending the winter in hibernation, and shed their skins as they grow (sloughing). Amphibians may be divided into two categories: those without tails (frogs and toads) and those with tails (newts and salamanders).
	Frogs and Toads Frogs and toads (Anura) are the best known amphibians because of their highly visible breeding behaviour. In both frogs and toads the tongue is attached at the front of the mouth and smacks out backwards to capture invertebrate prey on the sticky end, which is then curled round the prey and folded back down the throat. The eyes are used to help force the prey down by sinking them into the roof of the mouth! The two groups are easily distinguishable by their appearance. Frogs have damp skins which are covered with an oily secretion which helps to keep them moist and also makes them slippery for potential predators! They have strong, long back legs which help them to escape from danger and they jump freely. Toads have a drier skin covered with raised warts and weaker back legs. They tend to walk and can only hop short distances. Newts and Salamanders Newts and salamanders (Salamandridae) belong to the same amphibian group, although only newts occur in Britain - salamanders are found across Europe and the rest of the world. Newts have strong tails for swimming and are more secretive than frogs and toads. All common amphibians in Britain are protected from being sold as pets by the Government’s Wildlife and Countryside Act, which became law in 1981. The rarest species receive extra protection and require a licence for any scientific study.
	amphibians