How long do they live? Well, no one really knows and it’s been a debate for a while that the hydra may not age at all. Other researchers believe that the hydra could live up to 1,400 years under the right conditions. In a 4 year study of this tiny creature, they showed no signs of senescence [1], which is pretty impressive for an organism that reaches adult maturity between 5 to 10 days old. The Hydra may be a negligible senescent species when it is asexual, but research suggests that if it differentiates to a male or a female, then aging is detected [2]. So, basically no one knows what the hell is going on with these little guys/girls.

Where are they found? Pretty much anywhere there is fresh water in the world such as lakes, streams, and the puddle in your backyard.

What do they eat? Hydras are tiny carnivores that eat smaller creatures and fish eggs.

What do they look like? Some hydra can reach up to 10 mm in length and they look, well, they look like figure 1 and 2.

Figure 1. The tiny hydra. There are many types, but they all look similar.
Figure 2. The human who snapped this amazing photo is a wizard.

How do they reproduce? As I mentioned above,  hydras generally reproduce asexually by a process called budding. They literally produce a clone of themselves that buds off and goes on its merry way. In less than optimal conditions, such as decreased temperatures, the hydra can differentiate into male or female or both. The male releases sperm and the female takes in the sperm to fertilize eggs. As the eggs develop, the female dies. The males also show signs of aging in at least one study [2]. So, it’s better to be asexual, which is great news for some friends of mine.

So what are we lacking?  Follow up studies on pretty much everything – in science these days. One group found that the transcription factor, FoxO, controls longevity in hydra through maintaining telomeres [3], although more research is definitely needed. There is nuclear genome data on NCBI for hydra.



  1. Martı́nez, Daniel E. “Mortality patterns suggest lack of senescence in hydra.” Experimental gerontology 33.3 (1998): 217-225.
  2. Yoshida, Kengo, et al. “Degeneration after sexual differentiation in hydra and its relevance to the evolution of aging.” Gene 385 (2006): 64-70.
  3. Boehm, Anna-Marei, et al. “FoxO is a critical regulator of stem cell maintenance in immortal Hydra.” Proceedings of the National Academy of Sciences 109.48 (2012): 19697-19702.