When introducing a newcomer to frogs and toads a question usually arises about the difference between the two. This is a considerably more difficult question to answer than it may at first appear and simple answers may be misleading. Clear differences apply only between the frogs and the toads found here in Britain, or more precisely, between those members of the respective groups to which our native frogs and toads belong.
All frogs and toads belong to the order Anura, the tailless amphibians, differentiating them from the newts and salamanders which possess tails. Globally the order Anura consists of over 20 different families, of which only two are represented in Britain: the Ranidae, or ‘typical’ frogs, to which the native frogs belong and the Bufonidae, or ‘typical’ toads, to which the native toads belong. Between these two groups animals can quite easily be differentiated from one another, which historically led to them being distinguished as either frogs or toads. However, as more and more species across the world have been described and classified into other families, they have often been rather arbitrarily referred to as either frogs or toads, even though they may not necessarily conform to what we would recognise as either of the two. Some display characteristics of both, while others can barely be said to resemble either. This makes the two terms rather meaningless in any scientific sense and it is probably better to simply consider them all ‘Anurans’.
The typical Ranid frogs found here in Britain are slim waisted, smooth skinned creatures with long agile hind legs, making them powerful jumpers and swimmers. They possess dorso-lateral folds of skin which in many species extend the length of the trunk. Their spawn is produced in clumps, usually seen floating in shallow water surrounded by its gelatinous matrix.
The Bufonid toads by contrast are of a thick set build with shorter hind legs than the frogs, better equipped for walking than leaping. They have a dry, rough texture to the skin which is often described as ‘warty’; the warts consisting of tubercles and glands scattered across the body. The largest of these are a pair known as the parotid glands situated on the top of the head, one behind each eye. When the toad is molested these glands can secrete a powerful and distasteful toxin deterring many would be predators. The spawn is laid in long gelatinous strings, often wrapped around submerged vegetation and consequently is less conspicuous than that of the frog.
There are four anurans native to mainland Britain. Of these, only two are found in Somerset: The Common Frog Rana temporaria and the Common Toad Bufo bufo. Additionally, there is at least one introduced alien species in Somerset. This introduced species belongs to a complex of frog species collectively known as ’water frogs’ or ‘green frogs’, all within the genus Pelophylax.