灯塔水母可能是迄今为止自然界唯一长生不老的动物。

　　它们具有在成体和水螅体间不断循环的生活史,因此其寿命可以是无限的.科学家称这种水螅类水母是自然界已知的唯一一种可以返老还童恢复成水螅体(其生命的最初阶段)的动物。

　　这一现象如此神奇,其关键在于一个称之为转分化的过程——一种类型的细胞转变成另一种细胞.有些动物具有局部的转分化和器官再生能力,如蜥蜴的肢端可以再生.而灯塔水母具有整个身体反复再生的能力.研究人员试图弄清楚这种水母逆转衰老过程的机制。

　　由于可以绕开死亡,灯塔水母的个体数量非常庞大.它们源自加勒比海,如今已遍布全球海洋.史密森尼热带海洋研究院的Maria Miglietta博士称:"我们看到的是一个全球性的无声入侵。"

　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.