Adult frogs cannot breathe underwater—yet many drown
Amphibians are cold-blooded tetrapods that usually metamorphose from gilled larvae to air-breathing adults. Skin assists respiration; a few tiny lungless forms rely on it alone. Still, wildlife hospitals keep seeing frogs dunked in sealed aquaria by well-meaning people—adults generally drown without an exit ramp.
Living amphibians form Lissamphibia: frogs and toads (Anura), salamanders and newts (Caudata/Urodela), and caecilians (Gymnophiona). About eight thousand species are known, nearly ninety percent frogs. The smallest vertebrate, Paedophryne amauensis from New Guinea, measures seven point seven millimetres; the largest living amphibian is the roughly one point eight metre South China giant salamander. Greek amphíbios meant both kinds of life and once labelled any land-water animal, even seals.
They arose in the Devonian from lobe-finned tetrapodomorphs with early lungs, then dominated Carboniferous and Permian landscapes before amniotes took terrestrial primacy. Broad Amphibia is paraphyletic if it means all non-amniote tetrapods, including extinct temnospondyls and lepospondyls. Crown counts today list thousands of salientians across fifty-three families, hundreds of salamander species in nine families, and a couple hundred caecilian species in ten families, with records back to the Triassic.
Unlike reptiles, amphibians typically need moist habitats for eggs lacking amniotic shells. Metamorphosis swaps aquatic larval gills for lungs, yet cutaneous breathing remains crucial. The drowning myth-bust matters because popular culture still paints adults as fully aquatic. Conservation crises—chytrid fungus, habitat loss, pollutants—hit a clade already tied to water's edge. Understanding what amphibian actually means is the first step to keeping those eight thousand species from thinning further. Skin that doubles as a lung also makes the clade porous to pollutants and fungal disease, so population crashes often arrive first among frogs and salamanders. Keeping moist corridors and clean breeding ponds is less folklore than infrastructure for a Devonian inheritance.
Source: Amphibian
