Immortal Jellyfish

A potentially "immortal" jellyfish species that can age backward—the Benjamin Button of the deep—is silently invading the world's oceans, swarm by swarm, a recent study says.

Turritopsis typically reproduces the old-fashioned way, by the meeting of free-floating sperm and eggs. And most of the time they die the old-fashioned way too.

But when starvation, physical damage, or other crises arise, "instead of sure death, [Turritopsis] transforms all of its existing cells into a younger state," said study author Maria Pia Miglietta, a researcher at Pennsylvania State University.

The jellyfish turns itself into a bloblike cyst, which then develops into a polyp colony, essentially the first stage in jellyfish life.

The jellyfish's cells are often completely transformed in the process. Muscle cells can become nerve cells or even sperm or eggs.

Through asexual reproduction, the resulting polyp colony can spawn hundreds of genetically identical jellyfish—near perfect copies of the original adult.

This unique approach to hardship may be helping Turritopsis swarms spread throughout the world's oceans, she added.

Miglietta and her colleague Harilaos Lessios of the Smithsonian Tropical Research Institute in Panama compared the DNA of immortal jellyfish from waters off Spain, Italy, Japan, Florida, Panama, and elsewhere for their study, published in the June 2008 issue of the journal Biological Invasions.

Another mystery is how the jellyfish achieve their remarkable age reversal. Miglietta speculates that the creatures have very effective cellular repair mechanisms that allow them to age without incurring the usual ravages of time.

Miglietta dismissed news reports that implied the jellyfish could hold a key to anti-aging drugs for humans.

"Nobody is looking into that," she said, "and I don't think you're going to find any secrets in these creatures."

But while they won't yield the next Botox, the jellyfish just might help fight one of human health's greatest threats—cancer—according to biologist Stefano Piraino of the University of Salento in Italy.

Like cancer cells, "some cells of this jellyfish that were supposed to [die] … are able to switch off some genes and to switch on some other genes, reactivating genetic programs that were used in earlier stages of the life cycle," Piraino said.

By studying how exactly the immortal jellyfish's cells do that, he said, scientists may find clues for the struggle against that other silent, rapidly expanding invader. http://news.nationalgeographic.com/news/2009/01/090130-immortal-jellyfish-swarm_2.html