Amphibian

Amphibians are a class of vertebrate animals that typically live part of their life in water and part on land.

Amphibians are a class of vertebrate animals (Amphibia) that typically live part of their life in water and part on land. The living amphibians include frogs and toads, salamanders and newts, and caecilians. Most amphibians are ectothermic and many undergo metamorphosis from an aquatic larval stage to a terrestrial adult form.

Classification

Amphibians are vertebrate animals in the class Amphibia. Living amphibians are grouped into three orders: Anura, Caudata, and Gymnophiona. These correspond to the common groups of frogs and toads; salamanders and newts; and caecilians.

Life cycle and biology

Many amphibians undergo metamorphosis, beginning as aquatic larvae and later developing into adults with distinctly different body forms and habitats. Most amphibians are ectothermic, meaning they depend on external conditions to regulate their body temperature. Their skin is typically moist and permeable, aiding in water and gas exchange.

Habitat and distribution

Amphibians inhabit a wide range of environments including freshwater, terrestrial, fossorial (burrowing), and arboreal habitats. They are found on most continents but are absent from Antarctica. The greatest diversity occurs in tropical regions. In Canada, amphibians are represented by frogs, salamanders, and toads, though caecilians are not native.

Ecology and conservation

Amphibians are highly sensitive to environmental change due to their permeable skin and unprotected eggs. Many species face threats from habitat loss, climate change, pollution, disease, and other pressures. In Canada, amphibians are important components of wetlands, forests, and freshwater ecosystems, and several species are monitored for conservation concerns.