An immortal jellyfish
(Adapted from an article in curiosity.com)
Humans have long been fascinated by the prospect of living forever. Even in recent decades, high profile billionaires have spent their riches on up-and-coming technology claiming to help them achieve immortality. Before you get your hopes up, the secret to immortality is not necessarily putting a stop to aging. Instead, it might require reversing your life cycle back to the very first stage. At least, that's the method used by the Turritopsis dohrnii; also known as the immortal jellyfish.
T. dohrnii was discovered in the Mediterranean Sea in the 1880's, though it's since been observed off the coasts of Panama, Florida, Spain & Japan as well. Despite the fact it was familiar to scientists for more than a century, they didn't discover its strange ability until the 1990’s. When faced with starvation, physical damage, or an external threat, the jellyfish transforms itself into a polyp; its earliest stage of life.
Under normal circumstances, T. dohrnii reproduces the old-fashioned way: with sperm & eggs. But when faced with starvation, physical damage, or another crisis, it transforms its existing cells into a younger state through a conversion process known as transdifferentiation; the same process scientists use to turn stem cells into other human cells. During this stage, the jellyfish attaches itself to a sturdy surface, converts into a blob-like form, then transforms into a colony of polyps. It's the first known multicellular animal capable of reverting completely to a sexually immature stage after having reached full maturity.
It may be known as the immortal jellyfish, but that doesn't mean T. dohrnii can't die. They can still be killed, especially in their vulnerable polyp stage, by predators or illness. However, their small size keeps them hidden from most things in the ocean; a fully grown T. dohrnii is only about 4.5 millimeters (0.18 inches) across, about the size of your pinky nail. It's also mostly transparent, which makes it extremely hard to find.
As you might expect, the discovery of an immortal animal is of plenty of interest to medical researchers. By studying the transdifferentiation capabilities of T. dohrnii, scientists can further examine whether biological aging can be slowed down or reversed. It may be possible to follow T. dohrnii's lead by transforming our own cells into a younger state in order to reverse aging, sort of a marine version of Benjamin Button.
(Ed. note: "The Curious Case of Benjamin Button" was a film about a man who kept getting younger, sort of the reverse of progeria. Progeria is an extremely rare autosomal dominant genetic disorder in which symptoms resembling aspects of aging are manifested at a very early age. Progeria is one of several progeroid syndromes. Those born with progeria typically live to their mid-teens to early twenties.)
Woody Allen on the cycle of life:
“In my next life I want to live my life backwards. You start out dead and get that out of the way. Then you wake up in an old people's home feeling better every day. You get kicked out for being too healthy, go collect your pension, and then when you start work, you get a gold watch and a party on your first day. You work for 40 years until you're young enough to enjoy your retirement. You party, drink alcohol, and are generally promiscuous, then you are ready for high school. You then go to primary school, you become a kid, you play. You have no responsibilities, you become a baby until you are born. And then you spend your last 9 months floating in luxurious spa-like conditions with central heating and room service on tap, larger quarters every day and then Voila! You finish off as an orgasm!”
I would not advise eating a peanut butter & jellyfish sandwich----fishducky