Eight things salamanders and newts get away with

Threatened, the Iberian ribbed newt swings its sharp ribs forward — up to about 65 degrees — until the bony tips break right through pores in its flanks, turning its own skeleton into a row of venom-tipped spines. Glands flood the emerging ribs with toxin, so any predator that bites gets a poisoned jab in the mouth. Thanks to the newt's strong powers of regeneration, it heals the punctures and can perform the trick again and again.

North America's giant salamander barely uses its lungs — those mostly help it stay buoyant. Instead the hellbender breathes almost entirely through the deep, wrinkled folds of loose skin running along its body, which spread its blood supply over a huge surface and pull dissolved oxygen straight from cold running water. The flabby frills earned it the nickname 'snot otter,' and they only work in clean, fast, well-oxygenated streams.

The world's biggest amphibian is a salamander that can stretch to about 1.8 metres and weigh nearly 60 kilograms — long enough to reach an adult's shoulder. The Chinese giant salamander lives in cold, fast rivers, has tiny lidless eyes and poor sight, and tracks prey through ripples and pressure waves sensed across its wrinkled skin. Once thought to be a single species, it is now known to be several, and all are critically endangered.

A single palm-sized newt can carry enough tetrodotoxin to kill more than 20 adult humans, and there is no antidote. The rough-skinned newt loads its skin with this nerve poison — yet one predator eats it anyway. Common garter snakes where the newts live have evolved resistant nerve channels, so the two are locked in an escalating arms race: deadlier newts drive tougher snakes, which drive deadlier newts, repeated over millions of years.

An all-female lineage of mole salamanders has done without males for some five million years — the oldest known all-female vertebrates. They still need sperm, so they take it: a female courts males of up to five other salamander species and uses their sperm to trigger her eggs, sometimes folding bits of that borrowed DNA into her young. The result is a near-clone sisterhood whose cells can carry three, four or five different species' genomes at once. Biologists call it kleptogenesis.

A pale, blind cave salamander called the olm may be the longest-lived amphibian on Earth, reaching past 100 years. Sealed in the cold dark waters of European caves, it has skin-covered eyes, feathery external gills, and a metabolism turned almost off — it can survive up to a decade without eating a single meal. Tracked in the wild, individuals barely move for years on end. Slow living, it turns out, is very long living.

Most amphibians lay eggs in water, but the fire salamander gives birth to live young — and in some populations the unborn turn cannibal. Females carry developing larvae inside the body; where a brood is crowded, the largest embryos devour their smaller siblings and unhatched eggs before they are ever born, emerging as a few large, fully formed juveniles. Other populations simply release dozens of tiny aquatic larvae instead — all from the same black-and-gold species.