Amphibians
Permeable respiratory skin, transformative larval metamorphosis, and potent toxic alkaloids.
Amphibia
Amphibians are the original terrestrial pioneers. Most species live double lives: hatching as aquatic larvae with gills before metamorphosing into air-breathing land adults. Because their skin is permeable to water and gas, they absorb oxygen directly from the environment.
Key Evolutionary Adaptations
Cutaneous respiration allows many amphibians to absorb oxygen and water directly through porous skin layers.
Golden poison frogs carry enough batrachotoxin in their skin glands to stop the hearts of ten adult humans.
Axolotls retain larval external gills throughout adulthood and can fully regenerate severed spinal cords and limbs.
All Amphibians
Axolotl
The smiling cyber-amphibian that keeps its larval gills as an adult and can regrow whole legs and parts of its own brain and heart.
Cane Toad
Unstoppable neotropical chemical tank, turned loose in Queensland in 1935 to eat cane beetles, armed with shoulder glands whose toxins often kill the Australian native predators that try to eat it.
Common Frog
The frog that lives as far north as the Arctic Circle and sits out winter under rocks or buried in pond mud.
Fire Salamander
Black-and-yellow woodland amphibian whose glands behind the eyes secrete toxic alkaloids it can spray at attackers.
Glass Frog
See-through belly skin that shows off a beating heart, green bones, and a liver that can hide most of the frog's red blood cells.
Golden Poison Frog
Considered the most poisonous animal in the world: a frog no larger than a bottle cap that produces enough nerve toxin at once to kill 10 people.
Goliath Frog
The largest frog in the world, where males haul rocks to build nests for their eggs.
Harlequin Poison Frog
A rainforest frog just 2.5 to 3.8 centimetres long, painted like a warning label, its skin toxins collected straight from the ants, termites and beetles it eats.
Hellbender
North America's biggest salamander, breathing mostly through its own wrinkled skin instead of its lungs.
Japanese Giant Salamander
Up to five feet of living river boulder that breathes through its skin, hunts by smell and vibration, and gives off a peppery smell when stressed.
Olm
The cave salamander with eyes buried under its skin, a predicted lifespan past 100 years, and an experimental fast of a year and a half.
Pacific Giant Salamander
North America's largest terrestrial salamander, guarding Pacific Northwest streams with a startled bark, a noxious tail secretion, and gills it can keep for life.
Red-Eyed Tree Frog
A neon-green rainforest sleeper whose flash of scarlet eyes and bright flanks may give a predator pause long enough to escape.
Ringed Caecilian
A legless burrower about 40 cm long whose newborns eat their mother's skin and drink milk from her vent.
Strawberry Poison-Dart Frog
A 2-gram rainforest frog in warning colors, whose poison appears to come from the ants and mites it eats.
Surinam Toad
The flat, leaf-like toad that carries its developing young inside honeycomb pockets on the mother's back.
Wood Frog
A frog that can let ice fill over a third of its body each winter, stop its own heart, and thaw out alive again each spring.