Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, but some species have developed behavioural adaptations to bypass this. A list of amphibians organizes the class of amphibian by family and subfamilies and mentions the number of species in each of them. The list below largely follows Darrel Frost's Amphibian Species of the World (ASW), Version 5.5 (31 January 2011). Another classification, which largely follows Frost, but deviates from it in part is the one of AmphibiaWeb, which is run by the California Academy of Sciences and several of universities. The major differences between these two classifications are: Frost's ASW has split several families from other families (i.e. elevated to distinct families), whereas AmphibiaWeb has not (i.e., keeping them within the original families as subfamilies): From Dendrobatidae: Aromobatidae From Myobatrachidae: Limnodynastidae From Ranidae: Ceratobatrachidae, Dicroglossidae, Mantellidae, Micrixalidae, Nyctibatrachidae, Petropedetidae, Phrynobatrachidae, Ptychadenidae, Pyxicephalidae, Ranixalidae, Rhacophoridae AmphibiaWeb has also split a few families off from other families (i.e. elevated to distinct families), where Frost's ASW has not (i.e., keeping them within the original families): From Alytidae: Discoglossidae From Leiopelmatidae: Ascaphidae From Ambystomatidae: Dicamptodontidae From Caeciliidae: Scolecomorphidae, Typhlonectidae From Ichthyophiidae: Uraeotyphlidae Class Amphibia There are a total of 8216 amphibian species in three orders. Order Anura: frogs and toads , 7243 species of frogs and toads are recognised by Amphibian Species of the World. Suborder Archaeobatrachia Family Alytidae – painted frogs or disc-tongued frogs, 12 species. Includes the genus Discoglossus (5 species) which is sometimes considered a distinct family, Discoglossidae. Family Bombinatoridae – firebelly toads, 8 species Family Leiopelmatidae – New Zealand primitive frogs, 3 species in genus Leiopelma. Family Ascaphidae – tailed frogs. Two species in genus Ascaphus. Sometimes considered part of family Leiopelmatidae. Suborder Mesobatrachia Family Megophryidae – litter frogs or short legged toads, 268 species Subfamily Megophryinae – Asian spadefoot toads, 106 species Family Pelobatidae – European spadefoot toads, 6 species Family Pelodytidae – parsley frogs, 5 species Family Pipidae – tongueless frogs, 41 species Family Rhinophrynidae – Mexican burrowing toad, 1 species Family Scaphiopodidae – American spadefoot toads, 7 species Suborder Neobatrachia Family Allophrynidae – Tukeit Hill frogs, 3 species Family Alsodidae – 30 species Family Arthroleptidae – screeching frogs or squeakers,