The Jellies That Evolved a Different Way to Keep Time
3 days ago
- #circadian-rhythms
- #jellyfish
- #evolution
- Circadian rhythms are 24-hour biological cycles regulating hormones, metabolism, DNA repair, and more.
- Most species use a genetic system (CLOCK, BMAL1, CRY genes) for circadian timekeeping, found even in ancient lineages like sponges and jellyfish.
- A newly discovered hydrozoan jellyfish species has a unique 20-hour circadian clock, suggesting an independent evolutionary mechanism.
- This jellyfish lacks traditional circadian genes but still exhibits self-sustained, light-regulated rhythms, though temperature affects its cycle.
- The jellyfish's spawning is timed via a molecular countdown mechanism triggered by sunrise, with hormone accumulation dictating gamete release.
- Researchers plan to compare genomes of related jellyfish species to uncover the molecular basis of this unconventional clock.
- The study challenges traditional definitions of circadian rhythms and highlights the diversity of biological timekeeping mechanisms.