Jellyfishes are immortal, myth or fact?
Image Credit: Peter Schuchert/The Hydrozoa Directory
You might have probably seen somewhere on the internet, posts claiming that Jellyfishes are immortal, and wondered how can it be possible. Nonetheless this article digs deep into the truth behind those claims.
But before going into details about jellyfishes, specifically, Turritopsis dohrnii, being immortal or not, I think we should first ask this question: What is immortality?
Well, as the stories go, immortality is eternal life. “The ability of living forever.” Or it would be more clear if I say “the ability of never dying” because if you don’t die, you live…but how does one die?
According to Wikipedia there are three main causes of death:
Theoretically one who can conquer these three, lives forever.
But unfortunately humans haven’t gotten their hands on even one of these, but some animals have, like the Turritopsis dohrnii.
This species of jellyfish is rendered “immortal” by scientists, but why?
First discovered in 1883 in the Mediterranean Sea, it got under the hands of a scientist only in the mid-90's. Very little research has been conducted on this species, particularly because keeping it in captivity is quite a difficult task.
But interestingly in the recent years this species has spread rapidly through the world oceans. They have now been observed off the coasts Spain, Florida, Japan and Panama. Researchers explain that they might be hitching rides around the world in the ballasts of ships. Researchers have been calling the immortal jellyfish an “excellent hitchhiker” lately.
If we talk about their life-cycle, Turritopsis dohrnii start their life as a free-swimming larvae (known as planula) after developing from a fertilised egg. These larvae then settle down on the sea-bed, and start forming polyp colonies, known as hydroids. Hydroids buds off medusa, or what we call jellyfish. These new born jellyfishes are about 1 mm in size, to grow they feed and become sexually mature in a couple of weeks (depending on the temperature of the ocean).
Interestingly all the jellyfishes that pops up from a polyp are identical twins.
The adult medusa (or jellyfish) is bell-shaped with a diameter of about 4.5 mm, it has about 80–90 tentacles.
Now if the adult medusa is threatened or is injured or starving, it sinks to the sea-bed, converts into a blob, and returns to the polyp state, forming a new polyp colony, through a cellular process called transdifferentiation. In this process a cell, one that is specialised for a particular tissue, can convert into an entirely different type of cell. For example a nerve cell can become a muscle cell. And for the record this process is quite rare in the animal kingdom.
Theoretically, this process can go on indefinitely, effectively rendering the jellyfish biologically immortal.
Now biological immortality doesn’t mean the ability to never die… rather it means the ability to never age. The immortal jellyfish are likely to fall victim to dangerous hazards, such as eaten by predators or succumbing to a disease.
Doesn’t the idea of immortality make you a bit uncomfortable, while leaving you astonished?
Just imagine if you were an immortal jellyfish. It’d be like a man who grows old and old and one day starts ageing backward until he’s a fetes, just to start all over again. Or maybe a chicken which converts to an egg when threatened, just to hatch and wait to be hatched again.
References and further reads:
The strange life of the immortal Jellyfish -abc.net.au
Can a Jellyfish Unlock the Secret of Immortality? -Nytimes
Immortal Jellyfish- National Geographic