Can anyone explain the Turritopsis Dohrnii to me? The “immortal jellyfish, and one of the only immortal animals that we know of, but how? If it’s considered living then how does it not die?
In: Biology
For another interesting colony that changes form, have a look at termites which can also revert to larval form and become a different specialized member of the colony as needed.
From what I understand, and I could be wrong, they are “biologically immortal” in the sense that they would never die of old age due to how their cells are.
What makes them sweet is that they can revert back into polyps if they suffer any kind of trauma or non fatal injury, basically starting over. It would be like if we reverted back to a baby after losing like an arm or something. This poses risks of being once again super vulnerable though.
They are still vulnerable to disease and predation though, or damage too heavily sustained. I wonder what the longest one’s actually been alive for. I heard lobsters also share this feature.
Immortality is not invulnerability.
Additionally, it is considered immortal (I believe) because it is not considered to age, is cells don’t degrade as they reproduce.
Theyre not practically immortal, only theoretically immortal. They still die of diseases.
They have the ability through cell transdifferentiation to revert themselves to their immature polyp stage when stressed to form new clones of themselves, then reach maturity again, and then revert back again. This process can in theory take place over amd over without end, rendering them theoretically immortal. But in practical terms they get eaten or die naturally all the time.
Also – just a side note… aging and death are not prerequisites to quantify something as alive. Indeed there is some interesting research going on recently that suggests aging and death are evolutionary strategies, and not intrinsic processes…
example/ Cancer is a result of an error in the copying mechanisms involved in cellular regeneration… in theory long chains of telomeres could result in endless regeneration at tapid efficient scales, but would result in high volumes of errors leading to cancer that would kill organisms like people, before they reach sexual maturity and pass on their genes … so perhaps these chains evolved to shorten, leading to less efficient regeneration, but also slower and lower rates of cancer meaning more organisms live to mate, but also leading to old age and death… death, thus may ironically just be an evolutionary tradeoff for camcer prevention.
It can die. However, it has a unique ability that allows it to reverse a lot of the damage it will accumulate throughout life.
They can return to the polyp stage of their life cycle. This would be like an old man returning to an embryonic state.
As animals grow, cells differentiate into other types of cell. Stem cells are the start of this and become everything. However, once a cell becomes something, the amount of things it can now become is less. Basically this is a one way path.
These jellyfish can somehow reverse this process, and make differentiated cells into lesser ones. The exact mechanics are not fully understood.
Heyyy yo,
So Jellyfish aren’t actually a SINGLE living organism, they are a colony. So when they are damaged they dead colony members fall away and new ones are born. Most creatures cant reassign adult cells, but this one can. So it can quickly repair itself.
So like, if you break a bone, you gotta wait for more bone cells to form, this jellyfish can take arm cells and make them head cells if needed. Weird.
Question for someone a bit more versed in the biology literature than myself, do we actually know if T. Dohrnii is actually taking differentiated cells and reverting them back to the undifferentiated cell, or do the differentiated cells simply die off and are replaced by undifferentiated cells?
It seems to me that the term “immortal” in any species capable of asexual reproduction is a bit meaningless unless they are actually turning differentiated cells back into undifferentiated cells.
Any organism capable of asexual reproduction can create a new version of itself that will be genetically identical. If that process happens at exactly the same time as the “parent” is dying, then how do we differentiate between it rejuvenating itself and simple reproduction (and death) of a single new (old) organism?
These things are cool, but they aren’t nearly as special as pop science makes them out to be in terms of immortality.
First off, the species is possibly immortal but that doesn’t mean invulnerable, you can still kill them easily, and in the wild the die all the time from running out of food or getting eaten, things like that.
What makes the species special…well to explain, jellyfish have two lifecycle stages, first as little anemone-like things stuck to rocks, then as drifting jellyfish. In this species, the drifting jellyfish can turn itself back into the anemone-shape even after being a jellyfish, which is like a person being able to turn back into a baby, or a frog turning back into a tadpole or a butterfly turning back into a caterpillar. Which is pretty sweet.
That’s how they get reputation for being immortal…after all, if they can rewind their age they can live forever right?
Well…the truth is how long you can live has more to do with how your _cells_ are aging rather than what shape your body is, so merely being able to revert to juvenile shape doesn’t necessarily mean you can live forever. But on the other hand, this species _and_ many of its relatives (which can’t do the shape-revert trick) don’t seem to really age much or at all on the cellular level, so it’s likely that this species (but also quite a few other cnidarians) are basically immortal in the sense that they’ll just go on living indefinitely if nothing happens to kill them.
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