From animals that never seem to age to those which can survive for years without food or
water, here are 6 creatures that can live forever.
Number 6 Ocean Quahog This edible clam species is native to the
North Atlantic Ocean and renowned for its longevity.
After about 25 years, a period in which the clam grows and reaches sexual maturity, scientists
have found that its antioxidant enzymes maintained stable level for more than 150 years.
In many animal cells, the molecules that contain oxygen react with the cell membranes, thus
damaging parts of the cell.
However, the membranes from the cells of ocean quahogs are unusually resistant to this type
of damage, which means that these creatures age at a negligible rate.
An ocean quahog was discovered by British researchers off the coast of Iceland, in 2006.
The clam died when they opened its shell, in order to examine it.
At the time, the researchers weren’t aware of the clam’s age, which carbon dating would
later place at 507 years old.
The discovery received a great deal of media attention and journalists from the Sunday
Times dubbed the clam Ming, as it was born during the Ming dynasty, towards the end of
the 1400s.
The researchers later named it Hafrun, which roughly translates as ‘mystery of the ocean’.
There’s no way to tell how long the clam would have lived for if undisturbed from its
natural habitat.
Some have suggested that Ming might have been a rare example of biological immortality.
Number 5 Nematodes Nematodes are the roundworms which account
for about 80 per cent of all individual animals on our planet.
They’re present in every part of the Earth’s lithosphere, including desserts, mountains
and oceanic trenches.
They’re also found as parasites in the bodies of many vertebrates, including, in some cases,
humans.
According to nematologist Nathan Cobb ‘If all the matter in the universe except the
nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied
spirits, we could then investigate it, we should find its mountains, hills, vales, rivers
and oceans represented by a film of nematodes’.
Such is the ubiquity of nematodes on Earth.
Another incredible attribute is their ability of surviving in stasis for an extended period
of time.
In July 2018, Russian scientists collaborated with researchers from Princeton University,
to analyze around 300 prehistoric worms recovered from Russia’s Sakha Republic, above the
Arctic Circle.
The nematodes were found in permafrost and two of them began to move and eat after being
thawed.
One was believed to be about 32,000 years old, the other approximately 41,700 years
old.
This makes them the oldest living multicellular animals on Earth.
Number 4 Lobsters Research suggests that lobsters don’t stop
growing, weaken or lose fertility with age.
They grow through a process called ‘moulting’, during which the lobster sheds its hard exoskeleton
prior to growing a new one around a bigger body.
This process repeats itself with greater frequency when the lobster is young and then once every
two or three years after it passes a certain age.
Lobsters also retain their regenerative abilities, which enable them to regrow lost limbs, into
their advanced adulthood.
It’s theorized that the reason these blue-blooded creatures are often cited in the discussion
of biological immortality has to do with an enzyme called ‘telomerase’.
The chromosomes in animal cells have long repetitive sequences of DNA at their tips,
which are called telomeres.
As the cell divides and the chromosome is replicated, the telomeres become shorter,
in turn reducing lifespan.
Telomerase is an enzyme that repairs these chromosome tips and it’s expressed in most
vertebrates only during embryonic stages.
Lobsters, on the other hand, express telomerase in most of their bodies as adults, an aspect
which has been associated with their longevity.
Number 3 Planarian Flatworms These creatures are common to many parts of
the world, living in both saltwater and freshwater rivers and ponds.
Planarian flatworms have the reputation of being ‘immortal under the edge of a knife’.
That’s because these extraordinary creatures can be cut into pieces and each of them will
regenerate into a separate complete organism.
In just a few weeks, a full organism can be regenerated from a piece as little as one
279th of the already minuscule creature that it’s been severed from.
This is possible due to adult stem cells called neoblasts, which account for 20 per cent or
more of the total cells in the planarian flatworm.
They reproduce rapidly to replace older cells.
The existing tissue is remodeled to restore the proportion and symmetry of the new worm
that forms from a severed piece.
In the 1950s two American biologists carried out memory experiments on flatworms.
These experiments revealed that there’s a chemical basis for memory, which the researchers
dubbed memory RNA.
The working theory was that since ribonucleic acid encodes information, it might also be
used to record stimuli in neurons.
The researchers trained planarian worms to solve a simple maze consisting of bright lights
and electric shocks.
They then ground them up and fed them to untrained planarian worms to see how they would fare
in the maze.
The experiment concluded that those which had been fed trained worms associated the
bright light with shock faster than those that hadn’t.
This was attributed to the hormones from the ground animals which modified behavior in
those fed to them.
Even though the results of the experiment were somewhat debatable, subsequent research
proved that some memories can be stored outside the brain.
Although far from applicable in humans, the ability to transfer memories indefinitely
is typically regarded as a form of immortality.
Number 2 Hydra The Hydra is a type of fresh-water organism,
native to tropical and temperate regions.
These small creatures, which only grow to about 0.39 inches in length, are among some
of the most fascinating animals on Earth, for a number of reasons.
Their bodies consist of a simple adhesive foot, called the basal disc and, at the free
end, a mouth part surrounded by one to twelve tentacles.
Each of these tentacles is coated in specialized cells with structures called nematocysts,
which look like minuscule lightbulbs.
They contain a triggering hair on the outside and a coiled thread on the inside.
Upon contact with prey, the nematocysts explosively fire the dart-like thread, which contains
neurotoxins.
If many nematocysts are fired at once, their prey can become paralyzed.
Although these specialized attacks are interesting, they’re not the most astonishing aspect
about these creatures.
The hydra is, so far, the closest known animal to biological immortality.
Named after a mythological creature that was able to regrow its severed heads, the hydra
doesn’t appear to die of old age or even age at all.
This is because its stem cells have an indefinite capacity for self-renewal.
They’re so potent that the Hydra can regrow significant parts of its body, in case of
an accident.
When the hydra reproduces it typically grows tiny clones of itself on its body, which then
separate as they reach maturity.
Three distinct stem cell populations are used to replicate the tissues which form a fully
functioning animal.
All of them have a protein in common called ‘forkhead box O’ also known as FoxO.
It’s believed to be the key factor behind the Hydra’s immortality.
There are hopes in the scientific community that, by better understanding the Hydra, humans
will one day never have to worry about aging.
Number 1 Leopard Lungfish Leopard Lungfish, also known as marbled lungfish,
are found in swamps, floodplains and river deltas throughout Africa.
Their bodies can grow to nearly 7ft in length, with long tails that taper at the end.
Leopard lungfish also have very long and thin pectoral and pelvic fins, which are used to
glide through the water.
They draw their common name from the dark slate gray splotches that cover their fins
and bodies, creating a marble or leopard-like pattern.
These remarkable creatures have the largest known genome of any vertebrate.
At 133 billion base pairs, the leopard lungfish’s genome is also among the largest of any organism
on Earth.
Furthermore, studying the habits of this lungfish may provide a solution for unlocking suspended
animation in humans.
That’s because the lungfish can live on land, in riverbeds and other areas, that have
no freshwater available, for up to 5 years.
The fish will burrow into the ground to form an air bubble, which it breathes out of, as
it enters a dormant state called aestivation.
They slow down their biological clock, surviving in a low energy state in which they don’t
need sustenance.
Researchers, who’ve studied the leopard lungfish in its dormant state, have noticed
that it up-regulates genes related to detoxifying waste and down-regulated genes related to
blood coagulation.
This means that it simultaneously stops the build-up of harmful products in the liver
as well as conserving energy.
Once freshwater is available again, the fish emerges from its cocoon to resume feeding
and mating.
It’s believed that it can repeat this cycle indefinitely.
Replicating this ‘suspended animation’ in humans would allow astronauts to enter
hibernation during long space missions and doctors to buy more time when operating on
patients in critical condition.
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