The Incredible Way This Jellyfish Goes Back in Time

In the late 1980s two laboratory students collected a hydrozoan specimen they believed to be Turritopsis nutricula a tiny jellyfish less than a centimeter long where the individuals they collected were in their immature adult medusa form meaning they were not sexually mature yet where they placed the specimens in a tank hoping to breed them for research purposes and forgot all about them demonstrating how accidental laboratory oversight led to one of biology’s most revolutionary discoveries about aging and mortality.

The life cycle of this jellyfish starts when adult jellyfish in their recognizable medusa form swarm and release millions of eggs and sperm where most species will swarm in the hundreds or even thousands for reproducing where when a sperm successfully fertilizes an egg the fertilized egg will grow into a planula a tiny floating larvae demonstrating how jellyfish undergo complex metamorphosis through distinct developmental stages from microscopic larvae to recognizable adult form representing typical cnidarian life history strategy.

When this tiny jellyfish experiences high levels of stress starvation or physical damage it can send all of its cells back into a younger state where the jellyfish shrinks and retracts its tentacles and the medusa turns into a blobby structure called a cyst that settles onto the ocean floor just like its past self demonstrating how stress triggers complete ontogenetic reversal enabling escape from death through developmental regression unprecedented in animal kingdom.

The immortal jellyfish can do this amazing rejuvenation through a process called cellular transdifferentiation where this is when a cell of one type turns into an entirely different type of cell directly without turning into a neutral intermediate form first where studies have shown that the medusa doesn’t seem to contain stem cells so it must be the case that its existing cells are repurposed demonstrating how direct cell type conversion without dedifferentiation to pluripotent state challenges fundamental assumptions about cellular determination and developmental constraints.

The jellyfish seems to be able to protect and repair its telomeres where telomeres are strands of DNA found at the end of chromosomes and a bit like the plastic bits on our shoelaces they protect the rest of our DNA from damage especially during cell replication where every time a cell replicates a little bit of DNA is lost from the telomeres demonstrating how telomere maintenance through telomerase enzyme prevents replicative senescence enabling indefinite cellular renewal characteristic of immortal phenotype.

While in its cyst form Turritopsis dohrnii spends a good amount of its energy on internal upkeep in particular looking after its DNA where when in its cyst stage the jellyfish spends little effort on replication or cell differentiation which makes sense because it’s actively trying to prevent cells from specializing demonstrating how metabolic resource reallocation toward DNA repair and away from growth and differentiation creates optimal conditions for cellular rejuvenation and developmental reset.

Turritopsis dohrnii has worked well for the species where it’s fast taking over the world’s oceans where originally from the Mediterranean it’s believed that they have hitchhiked on boats and are now found almost everywhere where their resilience has probably helped contribute to their ability to survive across long distances and lots of environments demonstrating how biological immortality combined with anthropogenic dispersal vectors creates successful global invasion pattern transforming regional endemic into cosmopolitan species.

It’s unlikely that we’ll ever be able to Benjamin button ourselves but there are things we can learn from this jellyfish that could help us stave off some of the diseases that plague us later in life where transdifferentiation is an interesting field for scientists demonstrating how jellyfish cellular reprogramming mechanisms inspire medical approaches to degenerative disease treatment through direct cell type conversion without pluripotent intermediate stages enabling faster safer therapeutic applications.

Another area that the immortal jelly could shed light on is microRNAs where these are short strands of genetic material that regulate our DNA where they can switch genes on and off and are involved in DNA repair where we know that a lot of DNA repair is happening in a regenerating Turritopsis dohrnii demonstrating how small regulatory RNA molecules orchestrate complex gene expression programs enabling coordinated cellular transformation and DNA maintenance critical for successful life cycle reversal.