Death risk rose with age in asexual Hydra oligactis

In an experiment with Hydra oligactis, a freshwater animal, researchers tracked death rates and asexual reproduction across the animals’ lives. The animals descended from parent hydras collected in a pond in southern France. Researchers fed one group five times per week and another three times per week throughout their lives. They also recorded spontaneous tumours.

Death rates increased substantially with age, and the maximum observed lifespan was approximately two years. Animals fed three times per week had higher survival, indicating a dietary restriction effect. Higher rates of asexual reproduction were associated with a greater probability of survival. Tumour development was linked to lower survival. The findings showed that this species aged during its asexual stage.