Returning to the Beginning: An “Immortal” Jellyfish

Before bed, when the girls are with me, we read from two books. One page from our novel, currently The Horse and His Boy by C. S. Lewis, and a short devotional from How Great Is Our God: 100 Indescribable Devotions About God & Science by Louie Giglio. One night, that reading led us to a jellyfish called Turritopsis dohrnii, often referred to as the “immortal jellyfish.”

The key concept behind this species is transdifferentiation. Transdifferentiation is a "cell-level process where one mature, specialized cell changes into another type of mature cell." In other words, cells can switch roles. That matters because it explains how this jellyfish does something far more unusual .Another term connected to this process is ontogeny reversal. Ontogeny refers to "the development of an organism from early stages to adulthood." Ontogeny reversal is basically going backward along that developmental path.

When Turritopsis dohrnii experiences stress such as injury or harsh environmental conditions, the adult jellyfish does not die. Instead, it sinks to the seafloor and reverts to an earlier life stage called a polyp.

A simple (child) way to think about it is this:

• Transdifferentiation describes what the cells do.

• Ontogeny reversal describes what the jellyfish does.

Most animals follow a one-way biological path from development to aging to death. Under stress, this special jellyfish's adult cells reorganize, change identity, and rebuild the organism into a younger form. There is no reproduction, no embryo, and no return to stem cells. It is the same cells, reprogrammed. At the cellular level, muscle, nerve, and digestive cells begin changing roles.

Researchers have observed mature jellyfish tissue transforming directly into polyp tissue. This level of cellular identity change is extremely rare in nature. That's why Scientists are deeply interested in this species, because humans cannot do what they can. If similar processes were possible in humans, it could change how we approach aging, injury recovery, and degenerative disease. Early research suggests the jellyfish controls aging through changes in gene expression, rather than changes to DNA itself.

This is why Turritopsis dohrnii is called the “immortal jellyfish.” Not because it cannot be killed, but because it does not age in the usual biological sense. It doesn't avoid death. It escapes aging by rewriting what its cells are. Learning about this jellyfish stayed with me longer than I expected. Not only because of the science, but because of what it suggests about return, change, and identity. I also like this devotional series because it is not limiting to religion. I don't like religion. I like learning, curiosity, and seeing how science and faith can exist in the same space without being forced. After that reading and researching, I kept thinking about the idea of going back without erasing what you have already become. It felt like something I wanted to sit with in a different way than facts and definitions...aka the perfect inspiration for my next poem.