9I Immortal Jellyfish

Turritopsis dohrnii is a tiny hydrozoan jellyfish (adult bell ~4–5 mm across) native to the Mediterranean but now found worldwide, often called the "immortal jellyfish" for its unique ability to reverse its life cycle.

Under stress (starvation, injury, or aging), the adult medusa reverts to its juvenile polyp stage through transdifferentiation—cells reprogram into a younger form without dying. The polyp then buds new medusae, potentially repeating indefinitely. This makes the species biologically immortal (though vulnerable to predation/disease).

Discovery of Immortality

• Species first described in 1883 (Mediterranean specimens).
• Reversal discovered accidentally ~1988 by German student Christian Sommer in Portofino, Italy—he kept medusae in dishes and saw them regress instead of die.
• Confirmed/published in 1996 by Stefano Piraino, Ferdinando Boero, et al. in Biological Bulletin after years of lab work proving transdifferentiation.

Initial Rejection

The finding faced heavy skepticism for ~8 years because it violated the extended Dollo's law (complex traits/development can't reverse). Reviewers dismissed it as artifact or error; many biologists, influenced by Stephen Jay Gould's writings on irreversibility, considered it conceptually impossible. It took repeated experiments and microscopy evidence to gain acceptance, now it's a cornerstone for regeneration/aging research.

9I Immortal Jellyfish

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I am four millimeters
of living glass
in water the temperature
of your blood.

You spent ten thousand years
praying for ever-lasting life
building pyramids
swallowing mercury
begging your gods, for more time
uploading your minds
crying for just, one, more, day.

Then I arrived
and you called me
a problem, unlikely
You wrote your laws
said reversal's impossible
built cathedrals
to the word irreversible
squandered eight whole years
refusing to look at my miracle,
because Dollo and Gould
had already told you
what nature was allowed to do.

I never read them.
I never will.

When hunger or wound
or the slow insult of years
presses too hard,
I fold my bell,
pull my tentacles inward,
curl into a shocked comma
and sink.
Then I remember
every cell’s true name,
every pathway’s ancient pattern.

I become stem, again
not by forgetting,
but by reversed, clear memory
of what I was
before I ever became anything, none

I never read Gould.
I never will.

Polyp. Colony. Buds.
A hundred new bells
rise from my fallen body.
You call this cheating.
I call it
not being stupid enough
to accept your mathy dogmas.

You carried me in your bilges,
spilled me into every port,
then wrote papers
calling me invasive
because I refused to die
in the world you keep trying
to manage with borders
and warming charts
and clever warnings.

I do not read your books.
I do not care about your crises.
I simply refuse
to die by your schedule.

But I am waiting
in every drop of seawater
you still pretend to understand.
The answer you begged for
your whole history
is here, in me,
already immortal.
All you have to do
is stop being proud,
and look down and learn, copy my form

I never read Gould. I never read Gould.
I never will.

death, death, death, death, death, death
I never will.

death, death, death, death, death, death
I solved death
through remembering.

But you are still busy
proving how clever you are
at finding reasons
to stay mortal.

“When are you going to be done?”

after you.
        after you.
                after you.

This is the 9th animal in the memory music project.

Resources:

• The Incredible Way This Jellyfish Goes Back in Time