Nature is full of creatures that seem fragile at first glance—but some have mastered the ultimate survival trick: cheating death. From tiny water bears that can survive microwaves and space, to jellyfish that can rewind their own life cycle, these animals defy the rules of life and death in astonishing ways.
Meet the ultimate survivors, the masters of regeneration, and the immortals hiding in plain sight.
Immortal animals
Immortal jellyfish
It may not be truly immortal, but the jellyfish Turritopsis dohrnii is famous for being the only known animal capable of escaping death in an emergency. At first glance, it looks like little more than a tiny, brainless blob—barely the size of a blueberry—yet it possesses one of nature’s most extraordinary abilities.
- What is the biggest jellyfish in the world? Meet a monster jelly
- Meet the immortal animal that never dies
When the medusa—the dome-shaped, free-swimming adult stage we typically call a jellyfish—is injured or faced with a life-threatening crisis such as starvation, it can reverse its own life cycle. Essentially, it transforms back into its earliest developmental stage, like a grandmother reverting into a newborn.
Hydra
At one end, the hydra has a mouth surrounded by a crown of tentacles. Surprisingly, it has no heart, brain, eyes, or gills.
Meet the hydra: a tiny, unusual, and sometimes deadly creature capable of capturing prey much larger than itself—and potentially living forever.
What makes hydras truly remarkable is their ability to reproduce and regenerate. They can rapidly expand their populations through budding, growing new individuals directly from their bodies. Even more astonishing, hydras can essentially live indefinitely—if a hydra is cut into pieces, each fragment can develop into a complete, fully functional animal.
Flat worms
Few pond creatures are as astonishing as flatworms, thanks to their jaw-dropping powers of regeneration. While myths claim that cutting an earthworm in half will create two worms, that’s not true—but flatworms pull it off effortlessly.
- Discover the creature that can survive being sliced up by a knife
- No matter how it’s chopped, each fragment can grow into a fully functioning flatworm. Scientists still don’t completely understand how this works, but it’s made these tiny creatures legendary. As 19th-century naturalist John Graham Dalyell put it, flatworms are “immortal under the edge of a knife.”
Tardigrades
Tiny but unstoppable, tardigrades—aka “water bears”—are eight-legged micro-animals found almost everywhere on Earth. Don’t be fooled by their size: these creatures are basically indestructible.
Tardigrades can handle dehydration, microwaves, scorching heat up to 150ºC, freezing cold down to –273ºC, and even the vacuum and radiation of outer space
They can stay in suspended animation for over 30 years. Some scientists even claim that, with their incredible resilience, tardigrades could outlast nearly any other life on Earth—even surviving a nuclear apocalypse.
