From squirrels with major hibernation to beetles producing anti-freeze proteins, here are 10
animals that can freeze and come back to life…
10.
Arctic Ground Squirrel
Arctic ground squirrels are native to regions in Northern Canada, Alaska, and Siberia…
where they live on the mountain slopes, shores, and river flats of the tundra.
It's such an unforgiving environment, that the squirrels have developed unique adaptations
to survive… one of which is their ability to hibernate in sub-zero conditions.
Every winter, they dig deep into their underground burrows and will stay there for as long as
8 months.
Winter is looong sometimes!!
During this time, their body temperatures will fall to around 27 degrees Fahrenheit-
the lowest to have ever been measured in a mammal!
In this hibernation or torpor, their major organs slow down so much that they appear
to be dead.
Their bodily fluids are supercooled, which prevents them from freezing, and the squirrels
will wake once every three weeks or so, which is thought to be a way to ensure that their
brain survives.
Still, it’s risky business because many arctic squirrels don’t survive this extreme
state, but those that do will take less than a day to get back to normal once the weather
has warmed, and will begin mating straight away.
You know how it goes!
9.
Red Flat Bark Beetle
Red Flat Bark Beetles are a species of beetle found exclusively in the Arctic regions of
Canada and Alaska.
Small insects have two choices when the harsh winters close in- either give in to the cold,
or get through it by either tolerating the ice or filling their bodies with antifreeze
compounds.
It was long thought that the Red Flak Bark Beetles did the latter, where they lose as
much as 40 percent of their body water and replace it with the antifreeze proteins to
prevent ice forming… which would otherwise destroy their cells.
A recent study, though, has shown that the larvae can survive temperatures well below
freezing, and suggest they may use another process called vitrification- where the supercooled
bodily fluids turn into a viscous glass-like substance to prevent freezing.
Experiments showed that they actually produce antifreeze proteins to protect them as low
as -4 degrees Fahrenheit (-20°C), they then dehydrate which protects them to -40 degrees
(-40°C) , and then the vitrification kicks in that can protect them to temperatures as
low as a chilly -238 (-150°C) degrees.
The lowest temperature recorded on Earth was minus 129 degrees Fahrenheit recorded in Antarctica
in 1983, so they are all set no matter how cold it gets!
8.
Painted Turtles
Different species of turtles deal with cold temperatures in their own ways, but the Painted
turtles are undoubtedly the hardiest of them all!
They live across North America in ponds and slow-moving freshwater and have to be prepared
for ice sheets to cover them, with nowhere to go.
Luckily for the painted turtles, they have a number of tricks to help them survive.
The hatchlings are usually born in the fall, and bury themselves in the nest underground
during the winter.
They are able to supercool, which means their fluids don't freeze, and stay at temperatures
of around 28 degrees Fahrenheit (-2 °C) for three days.
Under certain circumstances they can withstand lower temperatures for much longer.
They’re able to recover quickly once they warm up, but this process isn’t always reliable.
If they are in moist soil, for example, the supercooling process may fail, but painted
turtles can still come back to life even if they’ve completely frozen- as long as it
hasn’t happened for too long.
In the water, painted turtles are able to absorb oxygen through their skin, mouth, and
other places, and can survive for months in a low or no oxygen environment.
To allow this, their metabolism can drop by as much as 99 percent, so they don't need
food or very much oxygen… and would appear to be dead.
Their bodies are able to take nutrients from their shells and skeletons to supplement their
needs during this time… something that can be replaced once things have warmed up.
Surprisingly, painted turtles need it to be cold for these processes to work.
If they’re trapped underwater in warm temperatures, their metabolism cannot slow down, and they’ll
soon drown.
And now for number 7, but first, can you guess the record for how long a critter has remained
frozen before coming back to life?
Leave your guess in the comments below.
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7.
European Crucian Carp
Each winter, as the lakes of northern Europe freeze over, the European Crucian Carps get
trapped in the water beneath.
At first, it seems that, once the ice thaws, the fish continue on with their lives as normal…
but things are more complicated here than they look..
The fish are able to stay alive during this time by relying on the glycogen that's been
stored in their bodies, in a process called glycolysis that transforms it into ethanol.
Their hearts can continue to function without oxygen and provide ethanol across their gills
to prevent them from becoming intoxicated.
Not every part of the fish is so impervious to the lack of oxygen caused by frozen environments,
though….
In particular, the brain.
Experiments have shown that, while there's no noticeable damage to the brain during the
winter, there's a drastic increase in the death of brain cells when they are initially
exposed to oxygen levels again.
This affects the fish's ability to perform tasks and rely on its memory, but fortunately,
this brain damage is only temporary…
European Crucian Carps are able to produce more cells and heal the affected regions,
meaning that they're back to normal functioning within a short period of time.
Unsurprisingly scientist are very interested in understanding this process more because
it could give clues on how to enable human brains to more effectively heal, or withstand
oxygen-poor environments for longer.
6.
Arctic Woolly Bear Caterpillar
While Arctic Woolly bear moths have similar lives to other moths, their caterpillars are
an entirely different story.
They live in the far north of the Arctic across Canada and Greenland, where they are exposed
to freezing temperatures for most of the year.
The caterpillars take around 7 years to collect enough nutrients to be able to transform into
a moth, so they need the ability to withstand the cold to be able to do this.
They actually spend most of the time at too low a temperature to be able to even move.
They require it to be at least 59 degrees Fahrenheit (15°C) to move around and feed-
something they are only able to attain by basking in the sunlight all day hoping that
the sun’s rays will provide enough warmth.
Arctic Woolly caterpillars freeze and thaw at least 7 times in their lives, and they
hide within rock crevices, surrounded by a light silk structure, known as a hibernaculum,
that provides just enough protection.
Their covering of hairs help to retain any heat they are able to absorb, and they produce
cryoprotectant in their blood and tissues that allows them to survive after being exposed
to temperatures as low as -94 degrees F (-70°C).
5.
Iguanas
We usually associate Iguanas with warmer weather, but as cold-blooded animals, they're also
very capable of dealing with colder temperatures.
When it gets colder than -40 degrees Fahrenheit, their bodies freeze and they become immobilized.
This causes unusual situations where, if the unfortunate iguana is in a tree at the time,
it simply falls to the ground- seemingly dead.
This happens a lot in places like Florida, where there are lots of Iguanas and, occasionally,
temperatures can plunge.
They aren’t dead, though, and once things warm up their blood returns to normal and
they come back to life.
Upon re-awakening, they can be quite angry and annoyed, so if you ever see an iguana
popsicle on the ground, it’s best to just leave it alone.
Whatever you do, don’t bury it!
4.
Upis Beetles
Upis beetles live in the same regions as the red flat bark beetles but have developed an
entirely different way of enduring freezing temperatures to ensure that they'll still
be alive for the thaw that comes in springtime.
They are a larger species and don't produce any antifreeze proteins to survive.
Instead, they produce a sugar-based antifreeze called xylomannan which attaches itself to
the outer cell membranes and physically prevents ice from entering the cell or forming within
it.
This allows the beetles to withstand temperatures of -76 degrees Fahrenheit (-60 C) without
freezing, and be ready for when things warm up to get back to their lives.
3.
Alligators
Alligators can be found in watery regions around the world, but have to return to the
surface periodically to breathe air to survive.
This can prove to be difficult when temperatures plummet, though, because the ice that forms
on top of lakes and rivers creates a physical barrier that prevents alligators from being
able to breathe.
Well, that’s what would happen if they hadn’t developed a unique way of solving the problem…
they allow the ice to form around their nose while the rest of their body remains under
the water.
If you’re ever passing a frozen lake where you know alligators live, have a look and
see if you can see any snouts sticking out above the ice.
This, of course, forces the alligator to stay in place…
essentially being frozen beneath the ice and unable to move until the temperatures warm.
As cold-blooded animals, the cold temperatures mean they have very little energy anyway,
so they’re more than happy to stay still until the heat returns.
2.
Tardigrades
Tardigrades are one of the hardiest types of creature on the planet, and cold temperatures
seem to pose no problem to them whatsoever.
Also known as water bears, they are water-dwelling organisms that measure up to one twenty-fifth
of an inch long, and they are known for their ability to survive deep depths and even the
vacuum of space.
In the cold, they enter a state of cryptobiosis, where all of their metabolic processes shut
down, and they show no signs of life.
In 2016, a team of Japanese scientists announced that they had brought 2 tardigrades back to
life… after having been frozen for 30 years.
While one of them died, another survived, and was even able to mate with another, and
create offspring… proving that the species can survive prolonged periods of freezing,
and keep going on despite some damage to their DNA.
Still, this doesn’t mean they can survive the longest of all animals in the cold, because
the record holder for the amount of time frozen is much more than 30 years!
Which brings me to:
1.
Nematodes
Nematodes are tiny worms, no longer than 1 mm, and have been seen to make wild adaptations
depending on the environment they’re in.
They can develop different mouths to adapt to the food that’s available, some have
adapted to high temperatures, they are the deepest multicellular organism to have ever
been found, and some have even adapted to be able to live inside the intestines of slugs.
A study in 2018 looked at 300 samples of Siberian permafrost, and two of them were found to
contain nematodes.
These females had been frozen in the ice for up to 32,000 years and miraculously came back
to life after being warmed up.
They were able to move and eat in what was the first known proof of natural cryopreservation,
and the longest known case of a multicellular animal being frozen and coming back to life.
Surprise!!
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