http://green.yahoo.com/blog/guest_bloggers/26/the-world-s-only-immortal-animal.html


The turritopsis nutricula species of jellyfish may be the only animal in the world to have truly discovered the fountain of youth.

Since it is capable of cycling from a mature adult stage to an immature polyp stage and back again, there may be no natural limit to its life span. Scientists say the hydrozoan jellyfish is the only known animal that can repeatedly turn back the hands of time and revert to its polyp state (its first stage of life).

The key lies in a process called transdifferentiation, where one type of cell is transformed into another type of cell. Some animals can undergo limited transdifferentiation and regenerate organs, such as salamanders, which can regrow limbs. Turritopsi nutricula, on the other hand, can regenerate its entire body over and over again. Researchers are studying the jellyfish to discover how it is able to reverse its aging process.

Because they are able to bypass death, the number of individuals is spiking. They're now found in oceans around the globe rather than just in their native Caribbean waters.  "We are looking at a worldwide silent invasion," says Dr. Maria Miglietta of the Smithsonian Tropical Marine Institute.

Bryan Nelson is a regular contributor to Mother Nature Network, where a version of this post originally appeared.

 

http://www.worldhealth.net/news/jellyfish_that_can_age_backwards_are_inv/


In most instances, Turritopsis reproduce like all species: the meeting of free-floating eggs and sperm. And for the most part, they die like all species. However, according to Maria Pia Miglietta, a researcher at Pennsylvania State University and author of a new study, in cases of starvation, physical damage or another crisis, "Instead of sure death, Turritopsis transforms all of its existing cells into a younger state," she says.
Through this process - called transdifferentiation - the jellyfish is able to return to its polyp state, the first stage of the life of a jellyfish. During transdifferentiation, its cells can become completely transformed. For example, a muscle cell could become a nerve cell - even an egg. The jellyfish then reproduces asɛҳuąƖly and breed hundreds of jellyfish that are identical to the original adult. This process can be repeated - again and again, but only as an emergency measure. As Dr Maria Miglietta of the Smithsonian Tropical Marine Institute says, "We are looking at a worldwide silent invasion."
This tiny creature, the size of a human pinky nail when fully developed, was first discovered in 1883. However, it wasn't until the 1990s that this unique ability to transform back into younger self once it has become sɛҳuąƖly mature and has mated was uncovered. Many marine biologists and geneticists are now studying the jellyfish in order to determine how it is able to reverse its aging process.