The secrets of the immortal jellyfish, Earth’s longest-living animal

Greenland shark lifespan: up to 500 years. Giant Barrel Sponge: Over 2,000 years. But what is the longest-living animal on earth? Immortal jellyfish, creatures that appear to be able to completely escape death.

Despite having an average diameter of just 3 millimeters, the adult form of this tiny invertebrate has a big trick up its sleeve. The idea is that when you are injured or on the verge of starvation, you can rewind your body’s internal clock. This means they could theoretically live forever.

But how exactly does an immortal jellyfish work?Turritopsis dohrnii) activates Doctor Who-The regenerative power of style? And can humans use this ability to completely eliminate aging? We’ll take a closer look at the science below.

How long do immortal jellyfish live?

Potentially forever. This is even more impressive when you consider that these creatures were floating in the ocean long before the dinosaurs went extinct (66 million years ago). It is biologically possible that an immortal jellyfish has been alive for this long time.

However, although this is technically possible, it cannot be proven. That’s because these jellyfish have only been studied sporadically since the early 1980s, meaning experts only have a few decades’ worth of data.

There is one more factor to consider. Immortal jellyfish can age adversely, but they can also be easily killed by predators such as various fish, sharks, turtles, and even other jellyfish. This is why immortal jellyfish are unlikely to pop up on Earth in large numbers in the near future.

How do immortal jellyfish live forever?

To understand how immortal jellyfish can hack their life cycle, we first need to take a closer look at how normal jellyfish age. Don’t worry, it’s very easy.Although very very strange.

Jellyfish life cycle © Getty
Jellyfish life cycle © Getty

Merely mortal jellyfish typically go through five life stages:

  1. Fertilized egg: Adult jellyfish (known as medusae) lay eggs and sperm in the water, and these two types of cells combine to form fertilized eggs.
  2. flame: The fertilized eggs develop into small larvae called planulae. They look like tiny insects and can swim freely.
  3. polyp: Planulae swim down to find a hard surface (such as the ocean floor) where they can develop a digestive system and feed themselves. When conditions such as water temperature are right, polyps reproduce asexually, creating clones of themselves and creating small colonies.
  4. Ephyra: After a new set of muscles and nerves is formed, part of the polyp (either the original polyp or a clone) becomes an ephyra, an organism that can swim, grow, and feed independently.
  5. Medusa: This is a fully grown adult jellyfish that can reproduce sexually with another jellyfish (although it usually dies quickly).

But when the Grim Reaper comes knocking, the immortal jellyfish upends this cycle.If you are starving, injured, or the water is too cold or hot, an adult should Turritopsis dohrnii Once they fall to the ocean floor, they transform into small clumps of tissue (known as cysts), which then become polyps again.

It can effectively move back and forth between Medusa and Polyp stages in its life cycle, making it almost biologically equivalent to Christopher Nolan’s work. doctrine.

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How can this happen? magic? Stem cells? close. This is an ability that is enhanced through a process known as transdifferentiation.

“This is basically when a fully formed specialized adult cell has the potential to become another type of specialized adult cell. That’s how cells adapt,” says Texas A&M University Galveston. explains Dr. Maria Pia Mirietta, associate professor at the school and head of the Real Immortal Jellyfish Research Project.

“Inside the cyst, the adult cells become necessary for the polyp and then, very importantly, are integrated back into the organism. In just a few days, the medusa can undergo metamorphosis and return to the polyp. there is.”

The exact mechanism behind transdifferentiation remains a mystery to scientists. But as Mirrietta explains, the answer is likely to be found in the jellyfish’s genes.

“It definitely has something to do with DNA,” she says. “It is DNA that programs a cell. Certain genes are turned on or off, which determines what type of cell it is.

“At the moment we want to understand what genes are turned on inside the cyst, because we think these are the genes involved in regeneration and the ability to escape death. is.”

Can humans become immortal like jellyfish?

After reading about how jellyfish seem to have acquired eternal life, you probably have one big question. How can we obtain that life? Unfortunately, immortal jellyfish can be full, but benjamin button There is still a long way to go before humans can freely master this level of differentiation.

“We are a long way from real-world applications,” says Mirietta.

“But by studying what’s going on inside these jellyfish, we can learn how those genes change their cells and how these changed cells compare to other cells. We hope that we will be able to find out how this is integrated. This is fundamental to understanding cell regeneration and tissue regeneration.”

“A lot of why we age is still a mystery. But by looking at this very simple animal using this very simple system, we can track some genes and discover that they You can know how to act.”

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Where do immortal jellyfish live?

Experts aren’t exactly sure where the immortal jellyfish came from, but they are now found primarily in tropical regions around the world. It’s all thanks to humans.

As Mirrietta’s research suggests, the creatures spread around the world after becoming entangled in ballast water (water that some ships add to their hull walls to stabilize them).

“We studied jellyfish from the Pacific, Panama, the Atlantic, Japan, Italy, Brazil and California. And in the genes I was looking at, they were all identical. If jellyfish had spread naturally. , these genes would have accumulated differences in different locations, but the identical genes indicate very recent human intervention.

“These jellyfish were then discovered in ballast water, suggesting how jellyfish migrate, an effect I call ‘silent invasion.’ ”

Everything you want to know about dinosaurs © Getty
Ballast water poured from a ship © Getty

Jellyfish may be readily available in tropical regions, but you should be warned now. Immortal jellyfish mean they make poor pets.

Indeed, leaving the larvae alone for several days without eating is not as scary as when my cousin forgot to feed his goldfish for a month (rest in peace). But if you throw this jellyfish into an aquarium, it’s likely to spend more time metamorphosing (and reverse metamorphosis) than actually floating.

“They are very sensitive to everything from water temperature to plankton and fish roe food,” says Mirrietta. “The real paradox is that it’s actually very difficult for them to stay alive!”

About our expert Dr. Maria Pia Milietta

Dr. Maria Pia Mirietta is an associate professor at Texas A&M University in Galveston and director of the Mirietta Laboratory, which focuses on the evolution, genetics, and ecology of jellyfish. She is also the director of the “True Immortal Jellyfish” research project and teaches a summer course on cnidarian biology at the Smithsonian Tropical Research Institute in Panama.

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