A jellyfish can age backwards
Turritopsis dohrnii can revert from a free-swimming medusa to a juvenile polyp, rewriting its life cycle instead of dying after spawning.
Strong2 min read
After stress or reproduction, the medusa settles and its cells transdifferentiate. Tentacles are resorbed. A stolon and a new polyp colony appear. The same genome, a younger body plan. Piraino and colleagues documented the reversal in the lab in 1996.
‘Immortal’ is the headline and the overclaim. Individuals are eaten, infected, and injured. The life cycle has no obligatory ageing cliff of the usual kind. In principle the loop can repeat. In the sea, something else usually ends it.
Caveats
- Reversal is demonstrated in culture. How often it happens in the ocean is poorly known.
- The cells are not ageless in the sense of zero damage. They change type and start over.
Sources
- 1Piraino S., Boero F., Aeschbach B., Schmid V.. Reversing the Life Cycle: Medusae Transforming into Polyps. Biological Bulletin 190, 1996.