How Some Animals Thrive Without Oxygen: Nature’s Hidden Survival Tricks

Most creatures need oxygen to provide the power to sustain life. It is what enables their cells, hearts, and minds to function. For humans and most creatures, a few minutes of zero oxygen is death.

Yet some remarkable animals live in places where oxygen is always scarce or sometimes completely absent. These species have evolved astonishing biological tricks that let them survive, stay active, and even flourish where most life would fail.

Learning how they do it not only increases our knowledge of biology, it may also help medicine and human health in the future.


Underground Champions and Extreme Survivors

Consider the naked mole rat, a small rodent that inhabits a crowded underground burrow system. The tunnels may plunge as low as a tiny fraction of the oxygen levels at the surface of the Earth. Most mammals would go into a panic in such a situation, but the naked mole rat is specially adapted for it.

According to a recent study in Nature Communications, naked mole-rats show unique metabolic and genetic changes that help them tolerate low oxygen. Their bodies store more glycogen than other rodents, enabling them to make energy even when oxygen is low, and they show high expression of certain genes associated with survival in low‑oxygen environments. Their hearts also build energy without producing damaging byproducts seen in other animals during oxygen shortages.

Other research has explored how these rodents cope at the cellular level. Naked mole-rats keep antioxidants active in their organs during hypoxia, which limits damage from oxidative stress even when oxygen is scarce. This ability to avoid cell damage under stress is unusual among mammals and helps them endure life underground.

Naked mole rats have even been observed in a suspended animation-like state when deprived of oxygen in a lab setting, switching from regular metabolism to anaerobic metabolism.

Turtles and Fish That Outlast Oxygen Starvation

Oxygen levels in the frigid northern lakes can almost disappear when ice covers the water in winter. Freshwater turtles in the Trachemys genus survive the winter in these lakes because they dramatically slow their metabolism.

In a long-term review of turtle physiology, scientists found that turtles have a balance in their use and production of energy so their heart and muscles continue to function even as their oxygen supply disappears. This control also regulates chemicals when oxygen re-enters.

Fish also have their own way of coping with low levels of oxygen. For instance, the crucian carp can survive for long periods without oxygen by slowing down its metabolic activities to a very low level.

A review published in the journal Acta Physiologica explains how carp manage to lower their metabolic needs, put their vital organs on standby, and recover quickly when oxygen is plentiful again.

There are also aquatic animals like annual killifish embryos that tolerate months of complete oxygen deprivation.

Research published in the Journal of Experimental Biology has shown that these embryos use special metabolic products, such as GABA, in order to survive for long periods of time without oxygen and protect their cells.

Amphibians and Intertidal Survivors

Amphibians, too, have some amazing survival plans. Research has shown that in the case of Siberian wood frogs, in times of extreme hypoxia, these frogs change their metabolic pathway in such a way that they use different end products of sugar metabolism in order to meet their basic needs.

Even tiny intertidal snails like the Littorina littorea can survive when the ocean tides pick them up and subject them to low-oxygen conditions. Studies show that these creatures change the manner in which their bodies use and produce energy, and this allows them to survive in extreme cold as well as anoxia.



Common Themes and Surprising Lessons

What these creatures seem to have in common is their ability to cut down sharply the amount of oxygen they need or find alternative ways of producing energy. They achieve this in many ways, including the ability to produce energy without the use of oxygen.

Each of the naked mole rats, turtles, fish, frogs, and snails demonstrates a different way in which life has adapted to a hostile environment, one that would be lethal for most other creatures. Each has rewired its genes and metabolism, slowed down its body functions, and provided its cells with protective mechanisms against the kind of damage that oxygen deprivation causes in most creatures.

Scientists think these changes developed over millions of years. By observing how these animals react to low-oxygen stress in real time, scientists hope to learn principles that could one day lead to treatments for human diseases such as stroke or heart attack, in which a lack of oxygen is a key factor.

Nature has shown us that the toughest environments cannot stop life from finding a way. These animals remind us that biology is flexible, resilient, and more imaginative than we think.