Immortal jellyfish can restart its life cycle

Found in temperate seas in different regions of the planet, this jellyfish belongs to the group of cnidarians, the same as corals and sea anemones.

Despite its tiny size and almost transparent appearance, its biological behavior defies the most common pattern among living beings and draws the attention of scientists.

How does the immortal jellyfish manage to “start over” its life?

The traditional life cycle of jellyfish alternates between the polyp stage, which remains fixed to the substrate, and the medusa stage, a free and reproductive phase. In the case of Turritopsis dohrniithis process can work as a continuous cycle.

When faced with stressful situations, such as lack of food, physical injuries or environmental changes, the adult jellyfish shrinks and turns into a cyst-like structure. From this reorganization, polyps capable of generating new genetically identical jellyfish appear again.

This phenomenon involves cellular reprogramming. Specialized cells regain the ability to transform into other types of tissue.

A study published in Proceedings of the National Academy of Sciences (PNAS), led by Maria Pascual-Torner, Victor Quesada and colleagues at the University of Oviedo, indicates that the species is the only known metazoan capable of repeatedly rejuvenating even after reproduction.

Biological immortality with natural limits

Because it manages to avoid progressive aging, this species of jellyfish is considered biologically “immortal”. This means that it does not have a natural life limit defined by the wear and tear of the organism.

In practice, however, it does not live forever. In nature, individuals can die due to predation, disease or severe environmental changes. The ability to restart the cycle can occur multiple times, but depends on conditions that allow reversal.

The genomic study also identified important differences in relation to closely related species considered deadly. Variants and expansions of genes linked to DNA repair, telomere maintenance, cell cycle control and response to oxidative stress were found.

These mechanisms help preserve genetic stability and reduce damage accumulated over time.

Although some cnidarians show limited forms of developmental reversal, only Turritopsis dohrnii maintains a high capacity for rejuvenation even after sexual maturity.

What does this discovery reveal about aging and science?

During the return to the juvenile stage, the researchers observed activation of pathways associated with cellular pluripotency and silencing of sets of genes linked to development, typical processes of biological reprogramming.

Understanding these mechanisms helps explain how certain organisms are able to repair damage and maintain tissue functionality for longer. Although there is still no direct medical application, knowledge can guide research into regeneration, age-related diseases, and strategies to prolong cellular health.

The existence of an animal capable of restarting its own biological trajectory shows that aging does not occur in the same way in all living beings and that the natural limits of longevity are still far from being fully understood.