9 Creatures That Can Survive Without Oxygen for Hours

Creatures That Can Survive Without Oxygen for Hours

Oxygen is essential for most life on Earth, but some incredible creatures have adapted the ability to survive without it for hours or even days. These animals have evolved complex physiological mechanisms that allow them to withstand oxygen deprivation.

In this blog article, we’ll explore 9 fascinating organisms that can live without oxygen and how they manage to do so. Understanding their ingenious survival strategies can provide insights into biology, evolution, and even potential medical advances.

Creatures That Can Survive Without Oxygen

1. Turtles

Turtles are renowned for their slow pace, protective shells, and ability to retreat into their shells when threatened. But did you know many turtle species can also withstand oxygen deprivation for stunning periods?

Freshwater turtles like painted turtles (Chrysemys picta) and red-eared sliders (Trachemys scripta elegans) can survive without oxygen for 30 hours at room temperature. At cooler temperatures, around 37-50°F (3-10°C), they can endure over 3 months in complete anoxia (total lack of oxygen).

How do turtles pull off such incredible anaerobic feats? When oxygen is scarce, turtles switch to slower anaerobic metabolism.

They also have large glycogen stores that supply glucose for energy production and buffer lactic acid buildup. Their slow metabolism lets them operate at reduced energy expenditure while shelled-up. Researchers are still exploring other adaptations that aid turtle anoxia tolerance.

2. Crucian Carp

Crucian Carp

The crucian carp (Carassius carassius) is a freshwater fish species notable for its hardiness – they survive in shallow, weed-choked ponds and flooded fields many species couldn’t withstand.

But the crucian carp’s most astonishing capability is surviving months in ice-covered waters utterly devoid of oxygen.

In anoxic conditions, crucian carp shift to anaerobic glycolysis fueled by liver and muscle glycogen stores. This produces only 5% of the ATP energy that aerobic respiration generates, letting crucian carp lower their energy requirements.

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Their livers also produce and store massive amounts of alcohol (ethanol), which later diffuses into the water and prevents metabolites like lactate from accumulating to toxic levels.

Remarkably, the crucian carp’s brain shows unusual activity patterns during anoxia. Sensory systems shut down, but areas controlling locomotion and behavior remain active, indicating crucian carp can coordinate complex behaviors even without oxygen.

3. Roundworms

Roundworms in bottle jar

Several roundworm (nematode) species inhabit intermittent environments like deserts and temporary pools. When these habitats dry up sporadically, the worms confront desiccation and oxygen deprivation until the next rains. Some roundworms evolved extreme anhydrobiosis capabilities to survive such phases for years.

The 1 mm long anhydrobiotic nematode Aphelenchus avenae fabricated a world record by recovering after 39 years in stasis.

Like the African midge, this roundworm dehydrates upon drying conditions until only 2-7% of its original water content remains. It conserves energy by entering hypometabolism with negligible oxygen need.

Through this desiccation-induced cryptobiosis, anhydrobiotic roundworms can essentially pause metabolism and development for decades before reviving. Studies of these worms identified new hydrophilic proteins involved in preventing fatal aggregation when cells dehydrate.

Further understanding of these creatures’ adaptations may enable better preservation of biologics like vaccines, cells, biomolecules or tissues.

4. Goldfish

Though often short-lived as pets, under natural conditions, humble goldfish (Carassius auratus) can survive up to 5 months encased in ice due to impressive anoxia tolerance adaptations.

Like their close crucian carp cousins, goldfish throttle down energy-intensive processes to reduce ATP demand without oxygen.

They achieve this through strong metabolic rate depression by downregulating unsustainable biochemical reactions and physiological processes. By entering hypometabolic comas, their core body functions tick over just enough to sustain viability until oxygen levels rise.

Extensive liver glycogen furnishes glucose to power anaerobic ATP production pathways that yield only 5% of aerobic respiration’s energy. But when oxygen is absent, such fermentation pathways are the only bioenergetic game in town – well worth just 1/20th normal ATP turnover!

5. Wood Frogs

Wood Frogs

The wood frog (Lithobates sylvaticus) inhabits forests ranging from the Appalachians to the Arctic circle and most of North America in between. It has the incredible capability to survive as a frozen frog popsicle at temperatures dipping under -4°F (-20°C) by halting its heart and ceasing metabolic function.

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When wood frog habitats start freezing over, 65-70% of their body water converts to protective extracellular ice masses.

Glucose from their liver glycogen and special cryoprotectant solutes shelter remaining fluid cells from freezing damage. Ice nucleating proteins in blood and tissues aid in controlling freezing, which is essential for surviving cryogenic stasis.

Without breathing or circulation for days to weeks, wood frogs enter suspended animation until spring thaws rouse them. They accomplish this by stockpiling fermentable fuels beforehand to sustain core energy needs when oxygen vanishes. Understanding this stress tolerance system has major implications for organ transplants and cryopreservation.

6. Green Frogs

Green frogs (Lithobates clamitans) rank among North America’s most cold-hardy amphibians thanks to specialized freeze tolerance adaptations. In northern climates, green frogs spend winters frozen in hibernacula burrows near pond bottoms, often for over 6 months without oxygen.

They prepare for subzero stasis by converting liver glycogen stores to glucose that packs cells to reduce freezing harm. Glucose transporters import sugars into select organs to concentrate cryoprotectants that prevent harmful freezing. Up to 45-57% of total body water solidifies into extracellular ice masses.

While frozen, green frog metabolism halts with no breathing or circulation. Anaerobic pathways assume minimal energy production for basic cell maintenance.

Freeze tolerance depends on ample energy substrate stockpiling beforehand via gluttonous pre-winter eating. Thermal hysteresis proteins also inhibit harmful ice recrystallization during thaws.

Understanding green frogs’ metabolic and physiological tricks may someday improve cryopreservation, transplant storage, and even space travel in frigid voids.

7. Siberian Salamanders

Siberian Salamanders

Siberian salamanders (Salamandrella keyserlingii) inhabit cold basins and alpine areas of eastern Russia and northern China. In ice-sealed Outer Manchurian lakes, these salamanders tolerate continuous frozen confinement below 3 feet (1 meter) of ice from November until April.

While suspended in freezing lakes for over 5 months without oxygen, Siberian salamanders accumulate high concentrations of glucose from liver glycogen breakdown. Glucose from enlarged glycogen reserves fuels anaerobic ATP generation and safeguards cells by direct cryoprotection.

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Up to 66% of their body water converts to extracellular ice masses during freezing. Ice-binding proteins spur harmless ice formation while inhibiting destructive recrystallization.

With freezing adaptation strategies advanced among amphibians, Siberian salamanders rank as record-setters. Their months-long frozen survival seems the apex of natural cryopreservation on Earth thus far.

8. Midge Larvae

Midge Larvae

Believe it or not, some insect larvae survive complete oxygen deprivation for years by dehydrating themselves into an inert form through a process called cryptobiosis.

The larvae of a midge (chironomid) species found in Niger an African midge (Polypedilum vanderplanki) holds the current animal record by enduring 17 years in an oxygen-null state.

The larvae prepare by filling its body with large amounts of trehalose, a natural cryoprotectant sugar. As oxygen levels vanish when ponds dry up, the larvae loses almost all its water content.

This prepares cells to vitrify into a glass-like substance stabilized by sugars when temperatures drop. Dehydration allows the larvae to practically cease metabolism and oxygen need until water returns years later.

Trehalose and other biological glassformers fascinated NASA astrobiologists seeking to preserve delicate mammalian tissues for space travel. Studying African midge larvae adaptations provided essential clues for developing successful cryptobiosis induction methods under controlled laboratory conditions.

9. Freshwater Turtles

Certain freshwater turtle species are champions of anoxia endurance due to their uncanny physiological adaptations. Red-eared sliders (Trachemys scripta elegans) and painted turtles (Chrysemys picta) can survive without oxygen at room temperature for 30 hours by switching from aerobic to anaerobic ATP production.

Painted turtles can push anoxia tolerance extremes to over 3 months at lower 37-50°F (3-10°C) temperatures by strongly suppressing metabolic demand. Their slow metabolism enables oxygen-independent ATP generation to match their reduced energy needs.

Both species also have high fermentable carbohydrate reserves in liver glycogen stores used to power anaerobic glycolysis for months.

How their organs endure this prolonged metabotoxin exposure remains scientifically puzzling – unlocking such secrets can reveal new treatments for reperfusion injuries from heart attacks, strokes, or blocked blood flow.

The Takeaway

Life on Earth requires oxygen for efficient energy production through aerobic respiration. Yet some incredible creatures can survive anoxia exposure for hours or months through metabolic flexibility to operate anaerobically.

By understanding such adaptations in turtles, frogs, fish, worms, and insects, science expands our comprehension of physiology while hunting for biomedical and cryopreservation breakthroughs.