Amphibians are members of the class Amphibia, a group of vertebrates whose living forms include frogs, toads, salamanders, newts and caecilians. They are characterized as non-amniote, ectothermic tetrapods, meaning their eggs are not surrounded by membranes, they are cold-blooded, and they have four limbs. Most amphibians lay their eggs in water and the larvae undergo metamorphosis from a juvenile form with gills to an adult air-breathing form wi...
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Amphibians are members of the class Amphibia, a group of vertebrates whose living forms include frogs, toads, salamanders, newts and caecilians. They are characterized as non-amniote, ectothermic tetrapods, meaning their eggs are not surrounded by membranes, they are cold-blooded, and they have four limbs. Most amphibians lay their eggs in water and the larvae undergo metamorphosis from a juvenile form with gills to an adult air-breathing form with lungs. Some, however, are paedomorphs that retain the juvenile water-breathing form throughout life. Mudpuppies and olms are examples of this, retaining juvenile gills into adulthood. Adult amphibians also use their skin for respiration.
The three modern orders of amphibians are placed in the subclass Lissamphibia and are the Anura (frogs and toads), Caudata (salamanders and newts) and Gymnophiona (caecilians, limbless amphibians that resemble snakes). The total number of known amphibian species is approximately 7,000. They are...
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