A chemical formula contains information on the types and spatial arrangement of bonds in the chemical. It also tells you what elements are in the chemical, and how many atoms of each. The spatial arrangement is not necessarily very obvious from the formula, e.g. C2H5OH does not tell you much about the spatial arrangement of the bonds. A chemical formula contains information on the types and spatial arrangement of bonds in the chemical.
All modern amphibians are included in the subclass Lissamphibia, which is usually considered a clade, a group of species that have evolved from a common ancestor. The three modern orders are Anura (the frogs and toads), Caudata (or Urodela, the salamanders), and Gymnophiona (or Apoda, the caecilians).
The class Amphibia is composed of only 3 orders. Anura, which refers to tailless amphibians, includes frogs and toads (see Table: Similarities and Differences Between Frogs and Toads). This is the largest order with more than 3,500 species. Caudata refers to amphibians with tailsâsalamanders, newts, and sirensâand has about 375 species (see Table: Some Common Salamanders and Newts). The Gymnophiona order is made up of caecilians, legless, tailless amphibians that spend most of their time burrowing. It has about 160 species.