Below are selected pictures of amphibians from around the world.
Except where noted, all images are the property of Rhett A. Butler, copyright 1994-2004. Contact me with questions regarding use, reproduction, or purchase of any of the pictures.
Panama golden frog (Atelopus zetecki) |
Green and black poison dart frog (Dendrobates auratus) |
Blue poison dart frog (Dendrobates azureus) |
Strawberry poison-dart frog in bromeliad |
Yellow-Banded Poison Frog (Dendrobates leucomelas) |
Boophis (?) frog at Andasibe |
Boophis frog, Masoala National Park |
Boophis tree frog |
Frog in Isalo |
Gray frog in Isalo |
Green Climbing Mantella (Mantella laevigata) |
Mantella madagascariensis (Painted Mantella) |
Tomato frog |
White's Tree Frog (Litorea caerulea) |
Rainforest frog in leaf litter |
Unknown frog with broad tan and brown bands and blue spots |
Tree frog in the tropical forest of Borneo |
Yellow and brown toad in Sulawesi |
Green Poison Dar Frog, Costa Rica |
Glass Frog, Costa Rica |
Monkey frog (Phyllomedusa bicolor) |
Monkey frog (Phyllomedusa bicolor) |
Monkey frog (Phyllomedusa bicolor) |
Hyla rhodopepla tree frog on leaf |
Hyla rhodopepla tree frog on forest floor |
Cane toad (Bufo marinus) in the Amazon rainforest of Peru |
Cane toad (Bufo marinus) in the wild |
Monkey frog (Phyllomedusa bicolor) |
Hyla tree frog species |
Hyla tree frog species
Amphibians (class Amphibia) are a taxon of animals that include all tetrapods (four-legged vertebrates) that do not have amniotic eggs. Amphibians (from Greek amphis "both" and bios "life") generally spend part of their time on land, but they do not have the adaptations to an entirely terrestrial existence found in most other modern tetrapods (amniotes). There are about 5,700 living species of amphibians.
The study of Amphibians and Reptiles is known as herpetology (Greek herpeton = to ramp and logos = word). The fear of Amphibians and Reptiles is known as herpetophobia (phobia = fear).
History of 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 they 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 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.
Solomon Berg Martin, Biology
Duellman/Trueb, Biology of Amphibians
Reproduction
For the purpose of reproduction most amphibians are bound to fresh water. A few tolerate brackish water, but there are no true sea water amphibians. Several hundred frog species in adaptive radiations (e.g., Eleutherodactylus, the Pacific Platymantines, the Australo-Papuan microhylids, and many other tropical frogs), however, do not need any water whatsoever. They reproduce via direct development, an ecological and evolutionary adaptation that has allowed them to be completely independent from free-standing water. Almost all of these frogs live in wet tropical rainforests and their eggs hatch directly into miniature versions of the adult, bypassing the tadpole stage entirely. Several species have also adapted to arid and semi-arid environments, but most of them still need water to lay their eggs. The larvae (tadpoles or polliwogs) breathe with exterior gills. After hatching, they start to transform gradually into the adult's appearance. This process is called metamorphosis. Typically, the animals then leave the water and become terrestrial adults, but there are many interesting exceptions to this general way of reproduction.
The most obvious part of the amphibian metamorphosis is the formation of four legs in order to support the body on land. But there are several other changes:
The gills are replaced by other respiratory organs, e.g. lungs.
The skin changes and develops glands to avoid dehydration
The eyes get eyelids and adapt to vision outside the water
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