New York, Dec 26: Is there a creature that can defeat death? Yes, says new research that confirmed that the tiny hydra - a centimetre-long polyp that inhabits fresh water all over the world - does not show any sign of deteriorating with age and, if kept in ideal conditions, may just live forever.
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.
"I do believe that an individual hydra can live forever under the right circumstances," said one of the researchers Daniel Martinez, professor at Pomo College in Claremont, US.
"I started my origil experiment wanting to prove that hydra could not have escaped ageing. My own data has proven me wrong - twice," Martinez noted.
He, however, said that the chances of a hydra living forever are low because they are exposed to the normal dangers of the wild -- predation, contamition, diseases.
Although scientists have known the hydra's regenerative capabilities, this latest research may possess the strongest evidence yet of its potential immortality.
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.
That scale, Martinez said, is key to the study's significance, along with the fact that the hydra showed constant fertility over time, defying expectations for most organisms.
The latest study took 2,256 hydra from two closely related species and conducted experiments in two laboratories over an eight-year period, doubling the amount of time from Martinez's previous experiments showing hydra living for four years.
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.
"Many, many hours of work went into this experiment," Martinez said.
"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 ageing," he said.
Explaining why hydras can carry on living without ageing while humans have to continue their search for the mythical fountain of youth, Martinez said that these tiny organisms are made of stem cells.
"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," Martinez noted.
"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," he explained.
The findings appeared in the jourl Proceedings of the tiol Academy of Sciences (PS).