Phylum Amphibia (amphibians)

Amphibians developed with the characteristics of pharyngeal slits/gills, a dorsal nerve cord, a notochord, and a post-anal tail at different stages of their life. They have persisted since the dawn of tetrapods 390 million years ago in the Devonian period, when they were the first four-legged animals to develop lungs.

During the following Carboniferous period, animals from the amphibia phylum also developed the ability to walk on land to avoid aquatic competition and predation while allowing them to travel from water source to water source. As a group they maintained the status of the dominant animal for nearly 75 million years.

Throughout their history they have ranged in size from the 15 foot long Devonian Ichthyostega, to the slightly smaller 6 foot long Eryops, and down to the tiny 1 centimeter long (24.7⁄64 inches) Psyllophryne didactyla, commonly known as the Brazilian Gold Frog.

Amphibians have mastered almost every climate on earth from the hottest deserts to the frozen arctic, and have adapted to climatic change with ease. Amphibians are taken to include all tetrapods that are not amniotes.

Class: Amphibia (6184 sp.)
- Order: Anura (5453 sp.)
  - Family: Alytidae (11 sp.)
  - Family: Amphignathodontidae (58 sp.)
  - Family: Aromobatidae (96 sp.)
    - Subfamily: Allobatinae (46 sp.)
    - Subfamily: Anomaloglossinae (22 sp.)
    - Subfamily: Aromobatinae (27 sp.)
  - Family: Arthroleptidae (132 sp.)
    - Subfamily: Arthroleptinae (81 sp.)
    - Subfamily: Leptopelinae (51 sp.)
  - Family: Bombinatoridae (10 sp.)
  - Family: Brachycephalidae (823 sp.)
  - Family: Brevicipitidae (26 sp.)
  - Family: Bufonidae (505 sp.)
  - Family: Calyptocephalellidae (4 sp.)
  - Family: Centrolenidae (146 sp.)
    - Subfamily: Allophryninae (1 sp.)
    - Subfamily: Centroleninae (145 sp.)
  - Family: Ceratobatrachidae (77 sp.)
  - Family: Ceratophryidae (85 sp.)
    - Subfamily: Batrachylinae (14 sp.)
    - Subfamily: Ceratophryinae (12 sp.)
    - Subfamily: Telmatobiinae (59 sp.)
  - Family: Cryptobatrachidae (21 sp.)
  - Family: Cycloramphidae (97 sp.)
    - Subfamily: Alsodinae (63 sp.)
    - Subfamily: Cycloramphinae (33 sp.)
  - Family: Dendrobatidae (164 sp.)
    - Subfamily: Colostethinae (53 sp.)
    - Subfamily: Dendrobatinae (52 sp.)
    - Subfamily: Hyloxalinae (57 sp.)
  - Family: Dicroglossidae (164 sp.)
    - Subfamily: Dicroglossinae (142 sp.)
    - Subfamily: Occidozyginae (22 sp.)
  - Family: Heleophrynidae (6 sp.)
  - Family: Hemiphractidae (6 sp.)
  - Family: Hemisotidae (9 sp.)
  - Family: Hylidae (844 sp.)
    - Subfamily: Hylinae (606 sp.)
    - Subfamily: Pelodryadinae (181 sp.)
    - Subfamily: Phyllomedusinae (57 sp.)
  - Family: Hylodidae (39 sp.)
  - Family: Hyperoliidae (207 sp.)
  - Family: Leiopelmatidae (6 sp.)
  - Family: Leiuperidae (77 sp.)
  - Family: Leptodactylidae (90 sp.)
  - Family: Limnodynastidae (44 sp.)
  - Family: Mantellidae (166 sp.)
    - Subfamily: Boophinae (54 sp.)
    - Subfamily: Laliostominae (4 sp.)
    - Subfamily: Mantellinae (107 sp.)
  - Family: Megophryidae (137 sp.)
  - Family: Micrixalidae (11 sp.)
  - Family: Microhylidae (426 sp.)
    - Subfamily: Asterophryinae (218 sp.)
    - Subfamily: Cophylinae (43 sp.)
    - Subfamily: Dyscophinae (3 sp.)
    - Subfamily: Gastrophryninae (40 sp.)
    - Subfamily: Hoplophryninae (3 sp.)
    - Subfamily: Kalophryninae (14 sp.)
    - Subfamily: Melanobatrachinae (1 sp.)
    - Subfamily: Microhylinae (68 sp.)
    - Subfamily: Otophryninae (3 sp.)
    - Subfamily: Phrynomerinae (5 sp.)
    - Subfamily: Scaphiophryninae (10 sp.)
  - Family: Myobatrachidae (82 sp.)
  - Family: Nyctibatrachidae (13 sp.)
  - Family: Pelobatidae (4 sp.)
  - Family: Pelodytidae (3 sp.)
  - Family: Petropedetidae (16 sp.)
  - Family: Phrynobatrachidae (76 sp.)
  - Family: Pipidae (31 sp.)
  - Family: Ptychadenidae (53 sp.)
  - Family: Pyxicephalidae (64 sp.)
    - Subfamily: Cacosterninae (59 sp.)
    - Subfamily: Pyxicephalinae (5 sp.)
  - Family: Ranidae (315 sp.)
  - Family: Ranixalidae (10 sp.)
  - Family: Rhacophoridae (286 sp.)
    - Subfamily: Buergeriinae (5 sp.)
    - Subfamily: Rhacophorinae (281 sp.)
  - Family: Rhinophrynidae (1 sp.)
  - Family: Scaphiopodidae (7 sp.)
  - Family: Sooglossidae (5 sp.)
- Order: Caudata (560 sp.)
  - Family: Ambystomatidae (37 sp.)
  - Family: Amphiumidae (3 sp.)
  - Family: Cryptobranchidae (3 sp.)
  - Family: Hynobiidae (51 sp.)
    - Subfamily: Hynobiinae (50 sp.)
    - Subfamily: Protohynobiinae (1 sp.)
  - Family: Plethodontidae (378 sp.)
    - Subfamily: Bolitoglossinae (249 sp.)
    - Subfamily: Hemidactyliinae (1 sp.)
    - Subfamily: Plethodontinae (93 sp.)
    - Subfamily: Spelerpinae (35 sp.)
  - Family: Proteidae (6 sp.)
  - Family: Rhyacotritonidae (4 sp.)
  - Family: Salamandridae (74 sp.)
    - Subfamily: Pleurodelinae (59 sp.)
    - Subfamily: Salamandrinae (15 sp.)
  - Family: Sirenidae (4 sp.)
- Order: Gymnophiona (171 sp.)
  - Family: Caeciliidae (121 sp.)
    - Subfamily: Scolecomorphinae (6 sp.)
    - Subfamily: Typhlonectinae (14 sp.)
  - Family: Ichthyophiidae (41 sp.)
  - Family: Rhinatrematidae (9 sp.)