What is the difference between a frog and a toad?
This is actually a tricky question to answer without a detailed discussion of how scientists classify plants and animals. The words frog and toad have been used for many hundreds of years. The word frog was originally used for the European Common Frog, which is a wet-skinned (slimy) animal living in or near water. The word toad applied to the European Common Toad, which is a dry-skinned animal usually living away from water. In the 1700s, Carl Linnaeus, a Swedish botanist, developed a simplified system for giving names to plants and animals. In this system, the European Common Frogs were given the name scientific Rana temporaria and the European Common Toads were given the name Bufo bufo. The common frogs and their close relatives were put into the family Ranidae and the toads and their relatives into the family Bufonidae. For example, the Northern Leopard Frog from America is closely related to the European Common Frog and has been classified as Rana pipiens. The Cane Toad is closely related to the Common Toad and has been named Bufo marinus. Therefore, the word frog only applied to the animals in family Ranidae and the word toad only for the animals in family Bufonidae.
Left: The Common Frog member of the family Ranidae, the True Frogs
Right: The Cane Toad member of the family Bufonidae, the True Toads
However, in the years that have passed since those early classifications, many more species of tail-less amphibians have been found, including some that are not closely related to animals in either of the families Ranidae or Bufonidae. For example, the common Australian Green Tree Frog, Litoria caerulea, is not closely related to the European Common Frog or Toad and is placed in the family Hylidae. That would mean that the Green Tree Frog should not be called a frog (as frog only refers to the family Ranidae). Around the world there are many tail-less amphibians that have characteristics similar to both Ranidae and Bufonidae but which are not closely related to either. Most scientists now agree that the word frog can be used to apply to all tail-less amphibians including those in family Bufonidae. Similarly, the word toad is often applied to tail-less amphibians that have dry warty skin, but it isn’t meant to be used as a classification tool. What this means is there isn’t really any difference between frogs and toads.
However, if you hear the term ‘true frog’ it only applies to the family Ranidae. ‘True toad’ only applies to the family Bufonidae.
According to the Guinness World records, the smallest frog in the world is the male Eleutherodactylus iberia, a frog from Cuba that only grows to about 8.5 mm. The largest is the Goliath Frog, Conraua goliath, from Western Africa, which reaches a length of about 40 cm and may weigh more than 3 kg.
Left: The smallest frog in the world! Right: The Goliath Frog, the largest frog in the world.
Amphibians have been on Earth for about 410 million years, so they have lived through all of the different environmental changes that have occurred during this time, including ice ages and other extinction events, like those that resulted in the extinction of the dinosaurs. The frogs alive today are very similar to those that first appeared about 240 million years ago.
