The tiny hydra - a centimeter-long polyp that inhabits fresh water all over the world - does not age and, if kept in ideal conditions, may just live forever, revealed researchers.
Hydra could live in ideal conditions without showing any sign of senescence - the increase in mortality and decline in fertility with age after maturity, which was thought to be inevitable for all multicellular species, the findings showed.
‘Hydra's body is made of stem cells with very few fully differentiated cells. They never age because stem cells have the ability to continually divide, and so a hydra's body is being constantly renewed.’
Researchers Daniel Martinez, professor at Pomona College in Claremont, US, said, "I do believe that an individual hydra can live forever under the right circumstances. I started my original experiment wanting to prove that hydra could not have escaped aging. My own data has proven me wrong - twice. The chances of a hydra living forever are low because they are exposed to the normal dangers of the wild - predation, contamination, diseases."
Working with James Vaupel of the Max Planck Institute for Demographic Research (MPIDR) in Rostock, Germany, Martinez duplicated earlier findings regarding hydra immortality, but on a much larger scale.
Martinez said, "That scale is key to the study's significance, along with the fact that the hydra showed constant fertility over time, defying expectations for most organisms."
For the project, each hydra was kept in its own dish and had to be individually fed three times a week with freshly hatched brine shrimp. The man-made freshwater in which the hydra lived needed to be changed three times a week.
Martinez said, "Many, many hours of work went into this experiment. I am hoping this work helps sparks another scientist to take a deeper look at immortality, perhaps in some other organism that helps bring more light to the mysteries of aging."
But why is this tiny organism able to carry on living while humans have to continue their search for the mythical fountain of youth?
Explaining why hydras can carry on living without aging while humans have to continue their search for the mythical fountain of youth, Martinez said that these tiny organisms are made of stem cells.
Martinez said, "Most of the hydra's body is made of stem cells with very few fully differentiated cells. Stem cells have the ability to continually divide, and so a hydra's body is being constantly renewed. The differentiated cells of the tentacles and the foot are constantly being pushed off the body and replaced with new cells migrating from the body column."
The findings appeared in the Proceedings of the National Academy of Sciences.