Biological immortality doesn't mean a creature cannot die (anything can be killed through sufficient trauma.) Instead, the biologically immortal creature cannot die due to old age - and you could say they possess eternal youth. Let's take a look at...
Certain cells have found a way to bypass the Hayflick limit. Cancerous cells reproduce quickly and without limit, something they do by producing the enzyme "telomerase." Telomerase rebuilds telomeres, meaning that cancer cells are biologically immortal - they will never die of their own accord. Healthy stem cells make use of telomerase in the same way.
There are samples of cancer cells grown in labs throughout the world today that have survived and proliferated for over seventy years. The HeLa line of cells were obtained from Henrietta Lacks, an African-American woman who died of cancer in 1951. The cells were (as was custom for the time) harvested without knowledge or consent, and were found to be particularly fast growing - making them ideal for human cell research. Samples of HeLa have contributed to the eradication of Polio, research into cancer and genetics... and have even been sent to space.
Mole rats show a similar disregard for aging - a mole rat has the same chances of surviving a year at age one as it does at age thirty. Again, this doesn't mean they can't die - just that they seem immune to the ravages of aging.
Hydra get their abilities from their cells. These animals are made up of stem cells that constantly renew tissue - and this means that every part of them contains the building blocks for a new hydra!
Thanks for reading - perhaps you'd also like...
- The Deathless Cells of "HeLa"
- Curmudgeonly Crustaceans
- Hale Hydra
- Attack of the Clones
- The Eternal Jellyfish
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| The amaranth was a symbol of eternal youth... (Anonymous) |
The Deathless Cells of "HeLa"
Human cells have an expiration date. The chromosomes of our DNA are protected by telomeres, "caps" that prevent them being damaged when producing a new cell. Unfortunately the protection these offer is ablative - and each time our cells divide a section of the telomeres is lost. Once a cell runs out of telomere, it can't safely divide. This sets a hard limit on the human lifespan - once cells lose the ability to divide and reproduce, they cannot be replaced when they become damaged or wear out. This is called the Hayflick limit, and applies to almost every cell in the human body.Certain cells have found a way to bypass the Hayflick limit. Cancerous cells reproduce quickly and without limit, something they do by producing the enzyme "telomerase." Telomerase rebuilds telomeres, meaning that cancer cells are biologically immortal - they will never die of their own accord. Healthy stem cells make use of telomerase in the same way.
There are samples of cancer cells grown in labs throughout the world today that have survived and proliferated for over seventy years. The HeLa line of cells were obtained from Henrietta Lacks, an African-American woman who died of cancer in 1951. The cells were (as was custom for the time) harvested without knowledge or consent, and were found to be particularly fast growing - making them ideal for human cell research. Samples of HeLa have contributed to the eradication of Polio, research into cancer and genetics... and have even been sent to space.
Curmudgeonly Crustaceans
Did you know that lobsters don't age, they just get bigger? While not biologically immortal, lobsters maintain supplies of telomerase in their cells that allow them to divide and grow indefinitely - a trait they pass on to the lobster, which can even regenerate lost limbs as a result. This ability to keep growing can lead to some surprisingly large lobsters, but it also seals their fate. Lobsters have to molt their shell to grow, and as they get larger, it gets more and more exhausting to do so. Eventually a lobster will grow so large that it cannot survive the energy expenditure required to molt and grow a new shell, and they will die - despite their cells being in excellent condition!Mole rats show a similar disregard for aging - a mole rat has the same chances of surviving a year at age one as it does at age thirty. Again, this doesn't mean they can't die - just that they seem immune to the ravages of aging.
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| Lobsters don't age -they just get bigger... (E2OMedia) |
Hale Hydra
Hydra are tiny freshwater invertebrates from the cnidarians, the same group as jellyfish. There's little to them aside from a foot, stomach, tentacles... and biological immortality. In the safety of a lab environment they do not age, but it doesn't stop there. Researchers have found hydra can regenerate sections of their body or reform after being dismembered. Researchers have even been able to "blend" hydra down to a cellular soup, only for a new hydra to form out of the organic residue.Hydra get their abilities from their cells. These animals are made up of stem cells that constantly renew tissue - and this means that every part of them contains the building blocks for a new hydra!
Attack of the Clones
It isn't just animals that reach for immortality. Hidden in Central Utah at Fishlake National Forest is the clonal organism known as Pando. The combined bulk of this entity covers 107 acres and weighs in at around 13 million pounds, consisting of approximately 47,000 aspen trees springing from a massive singular root system. Though estimates of its age vary wildly, researchers suggest it may have taken root between 16,000 and 81,000 years ago!Unfortunately, Pando may be hitting the twilight of its existence - as animals are consuming many of the clone saplings produced by Pando before they can become established.
One jellyfish has found a way to short-circuit the life cycle. The medusa of Turritopsis dohrnii can choose to revert back to the polyp stage when badly hurt or starving. The process begins with the tentacles being reabsorbed by the body of the medusa, before it settles onto the sea floor as a small organic blob. This blob then grow back into a polyp and eventually bud off into medusa again when the situation has improved.
Because the polyp stage of the jellyfish has a large number of cells and organs not found in the medusa stage, reverting allows the creature to rejuvenate itself and outright grow a new body. There doesn't seem to be any limit to how often this process can be accomplished - researchers believe that (under perfect conditions) the "immortal jellyfish" need never die.
The Eternal Jellyfish
Jellyfish all follow a similar life cycle. Their life-cycle begins as a free-swimming larva that eventually lands on and adheres to a solid surface. At this point, the nascent jellyfish will anchor itself and grow, maturing into a polyp. Finally, the polyp will bud off the adult form of a jellyfish, known as a medusa.One jellyfish has found a way to short-circuit the life cycle. The medusa of Turritopsis dohrnii can choose to revert back to the polyp stage when badly hurt or starving. The process begins with the tentacles being reabsorbed by the body of the medusa, before it settles onto the sea floor as a small organic blob. This blob then grow back into a polyp and eventually bud off into medusa again when the situation has improved.
Because the polyp stage of the jellyfish has a large number of cells and organs not found in the medusa stage, reverting allows the creature to rejuvenate itself and outright grow a new body. There doesn't seem to be any limit to how often this process can be accomplished - researchers believe that (under perfect conditions) the "immortal jellyfish" need never die.