What is a frog?
Frogs are amphibians. The word amphibian comes from the Greek words ‘amphi’ and ‘bios’, which loosely translates to 'living a double life' or ‘living on two sides’. This is because most amphibians lay eggs in water. The eggs hatch into larvae (tadpoles), then grow and change into little frogs which live on land. This growth and change is called metamorphosis. In other words, at one point in their lives they live in an aquatic habitat (water) and at another point they live in a terrestrial habitat (land). However, there are many amphibians that have very different life cycles; some don’t even have tadpoles living in water!
Amphibians are ‘cold-blooded’ vertebrates. i.e. they have a back bone and control their body temperature by moving between hot and cold areas in the external environment. They usually have smooth, moist, semi-permeable skin. This means that they don’t have hair, scales or feathers to protect them and water is able to pass in and out of their bodies straight through their skin.
There are three different groups of amphibians living on the planet today. These are the tail-less amphibians (frogs and toads), the tailed amphibians (newts and salamanders) and the leg-less amphibians (caecilians). In Australia, the only native amphibians we have are the tail-less amphibians, although many people have pet axolotls, which are the tadpoles of a Mexican salamander.
Left: Green Tree Frog, a tail-less amphibian. Right: Spotted Salamander, a tailed amphibian
Caecilian, a leg-less amphibian