Today I found out there is a species of jellyfish that can age both forwards and backwards, making them theoretically immortal.

Most jellyfish have a lifespan of between a few hours to a few months, though a few varieties can live for several years.  The king of them all in terms of biological lifespan is the Turritopsis Nutricula which can potentially live forever.  They can grow old like every other living thing, but then have the unique ability to reverse this process and grow young again.  Of course, their bid for immortality is hindered by the fact that they only grow to a maximum of around 1/5 of an inch in diameter on their bell, so they are easy prey for many animals.  However, in theory, they can live forever; the only known living thing to be able to achieve this.

The Turritopsis Nutricula begins life much like most jellyfish.  The male jelly will release its sperm into the water and it may unite with the egg of a female jelly.  Eventually this will produce planulae (free swimming larva) that leaves the body of the female jelly and float around until finally settling on the sea floor and attaching to something sturdy like a rock.  It then forms into a stationary polyp that will eventually look like a plant.  This polyp feeds on various things like plankton and over time a colony of polyps will form from the single polyp, all connected via feeding tubes.  At a certain point, sometimes even years later, the colony of polyps will begin producing free swimming jellyfish.

Also like most jellyfish, the Turritopsis Nutricula, once they’re formed into jellyfish, float away with the currents, gathering food as they encounter it.  The real miracle of the Turritopsis Nutricula, though, is what happens when food is scarce or they are injured or various other environmental queues occur.  These events will trigger a unique mechanism within the Turritopsis Nutricula that causes it to begin to grow younger via transdifferentiation, where their cells are able to change themselves into a new cell.  They continue to grow young all the way to the point where they once again become a single polyp, starting the process all over again.  They will then remain a polyp for a time, even able to grow a new colony.  Once again, at a certain point, free floating jellyfish form and are released from the polyp colony, each with the same genetic code as the original jellyfish that formed the polyp.  It is thought that this process can go on without end, assuming the resultant jellyfish don’t die of some disease or aren’t killed by some predator.  This effectively makes this tiny jellyfish biologically immortal.

If you liked this article, you might also enjoy our new popular podcast, The BrainFood Show (iTunes, Spotify, Google Play Music, Feed), as well as:

• How Porcupines Mate
• How Honeybees Keep Their Hives Warm Even Though They are Cold Blooded
• Clownfish are All Born Male
• Why Cats Like Catnip
• The Difference Between a Donkey and a Mule

Bonus Facts:

• It isn’t just fully grown Turritopsis Nutricula that can revert back to the polyp stage.  At any point from the time they emerge from a polyp to being fully mature, their bodies can revert back to the polyp stage if environmental factors warrant it.
• Jellyfish sting you through nematocysts.  Nematocysts are tiny spine covered tubules.  The spines anchor themselves in your skin and when the nematocysts fire, various chemicals are injected into you.  In some cases, you may have literally thousands of these nematocysts attached to your skin after being stung by the jellyfish.
• Even after the jellyfish is dead, they can discharge nematocysts, sometimes even days after the death of the jelly, which is why you should be careful playing with a dead jellyfish on a beach.
• If you’re stung by a jellyfish, a good remedy for this is to pour vinegar on the area stung, which will neutralize the nematocysts.  The exceptions to this are if you got stung on your eye (you shouldn’t put vinegar in your eye) or you were stung by a Man o’ War (vinegar will make their stings worse).
• You should never wash the sting with fresh water as it can change the tonicity, causing the nematocysts to fire, injecting more chemicals into you, which obviously makes the problem much worse.  For the same reason, you should NOT apply ice or urine to the affected area. Rather, if no vinegar is available, you should rinse it with salt water, then use a knife, razor, credit card, etc. to very gently scrape (don’t use very much pressure or it will cause the nematocysts to fire) the area stung  to get rid of any remaining nematocysts before they fire and make the problem worse.  Finally, dry the area off as best you can without using too much pressure.  Taking an antihistamine, such as Benadryl, will also help.
• Jellyfish can be found in every ocean and there are even certain kinds of freshwater jellyfish, though these don’t sting.  It is thought jellyfish first came into being around 500-700 million years ago, making them the oldest of all multi-organ living things on Earth.
• Because jellyfish are not actual fish, many institutions, such as public aquariums have settled on referring to them non-scientifically as “jellies”, rather than jellyfish.
• A group of jellies is called a bloom or a smack.  Blooms as large as around 100,000 jellies have been observed.
• The majority of jellies do not have what we would consider a brain.  Rather, they simply have a network of nerves which allow them to respond to various things in their environment.  However, it should be noted some not only possess a brain, but actually have multiple brains.  For instance, the Box jelly has four brains that act in parallel with one another.  They also have 24 eyes, including two eyes that have a cornea and a retina and which are able to see colors.
• What type of jellyfish is the largest in the world depends on one’s definition of “largest”.  That being said, two of the main candidates are the Lion’s Mane jellyfish, which can grow tentacles up to 120 feet long, and the Giant Nomura Jellyfish, whose bell can grow as big as 7 feet in diameter (about twice as big as a Lion’s Mane Jelly) and can weigh as much as 440 pounds.