About Amphibians

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is a class of tetrapod vertebrates comprised of three orders: Frogs (Anura), Salamanders (Caudata), and Caecilians (Gymnophiona), each with a distinctive general body type.

"Amphibian" comes from the Greek "amphi-" and "bios" meaning "of both or double kinds" and "life" or "living", referring to the generalized life history trait of amphibians undergoing metamorphosis from an aquatic larval form into a terrestrial adult. Many frog and salamander species have a "double" life of relying on water for their aquatic stages (e.g., tadpoles, larva) to eventually metamorphosizing into a fully terrestrial adult form.

Bufo americanus, photo by Brad Moon Bufo bufo tadpole, photo by Frank Tiegler Bufo bufo metamorph, photo by Peter Janzen

General Biology

Amphibians are ectothermic, regulating their body temperature with behavior as they rely on the ambient environment for their body temperature. Many temperate species can function at very low temperatures, and some in fact, have specific proteins in their blood to help them withstand periods of freezing (e.g. Rana sylvatica). Amphibians have soft, unscaly, permeable skin with many glandular properties that we are only beginning to discover. Their skin is protected with a layer of mucus which also helps them absorb environmental cues and oxygen. In fact, the most speciose family of salamanders, Plethodontidae, is entirely lungless, using their skin surface for respiration. Amphibian skin glands also produce toxins, some at lethal doses to other vertebrates, especially for would-be predators. Investigating the antimicrobial properties of amphibian skin glands is an area of promise for medical and pharmaceutical applications (e.g., Xi et al 2013).

Amphibians are globally distributed except in the polar regions of Antarctica and Greenland, especially concentrated in the neotropical countries. They inhabit a variety of ecozones, from rainforests to deserts. They display a diversity of life history and reproductive strategies to suit almost all ecoregions, and yet, many details of amphibianís biology still elude us. New species continue to be discovered in both remote and sometimes surprisingly accessible places (e.g., a new leopard frog discovered in New York City in 2012).

We track new species here.

With this increasing knowledge and discovery of amphibians, we simultaneously face rapid declines of amphibian species worldwide. It is a profoundly disturbing paradox which AmphibiaWeb attempts to both document and address by connecting resources and knowledge to researchers, students, and the concerned public.