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.


WIKI了一下，是灯塔水母。
“普通的水母在有性生殖之后就会死亡，但是灯塔水母却能够再次回到水螅型。成熟的个体经过收缩触手、外伞反转、体型缩小等步骤，能够重新在物体上着生，成为水螅体。能够反转生活史的这种能力在动物界极为稀有，也让灯塔水母免于老死。
根据报告显示，在获得有性生殖能力之前，朝着动物胚胎发生生长的个体再度回到未成熟状态的后生动物只有灯塔水母和Laodicea undulata。这被称作细胞转分化（transdifferentiation）。理论上这个过程没有次数限制，这两种水母可以通过反复的通常生殖和转分化获得无限的寿命。所以也被人称为“不老不死（的水母）”。不过更准确地说应该是“返老还童”。”
这个东西美啊