Like many jelly species, members of the group Hydra have a polyp stage that reproduces asexually by budding off little clones, and people have speculated this could last for thousands of years. So Daniel E. Martínez closely watched members of one species, Hydra vulgaris, for 4 years, and in that time very few animals died [3]. Dr. Martínez suggests that since animals that start reproducing only a few days after birth, such as Hydra, tend to kick the bucket earlier than animals that wait, 4 years is a pretty long time. But does that really mean they’re immortal?

More information is needed about Hydra, but it’s not the only species people keep for decades, nor the only species that could help us understand if some jellies may last forever. So, to get to the bottom of this I polled the experts.  I sent emails to some of the top jelly aquarists asking: do polyp clone populations change over time?

Most public aquaria display jellyfish, and to do this they take advantage of the peculiar jelly life cycle.  The life of jellies is broken into two parts: the polyp-type stage, which looks like Hydra and divides asexually, and the jelly stage, which grows from polyps and gets on with the busy act of sexual reproduction. To keep the number of exhibit jellies constant, aquarists use polyps as a literal clone bank, cueing them to produce more jellies as needed.

And do these clone banks ever change or grow old? The answer was a unanimous “yeah, kinda.” According to aquarists at both the Monterey Bay Aquarium and the New England Aquarium, over about six years clonal populations do get “tired.” They become more fragile, don’t produce healthy jellies, and stop responding to environmental signals. Many aquarists replace their polyp stocks with new baby polyps quite regularly, so that none of this fickleness gets in the way of jelly production. The whole colony may continue to kick, but it gets more and more fragile over time. To me, this sounds a lot like aging.

When humans die it’s not because a special gene turns on that shouts: “YOUR TIME IS UP!” Rather, little things start breaking all over, cells stop dividing and those that do accumulate mutations, this is why getting older is often accompanied by all sorts of biological issues. The truth is, accumulating mutations and cell gunk isn’t something special about aging people, even clone lines of E. coli bacteria accumulate harmful cellular products over time [4]. This is just the cost of being alive. So does the “immortal jellyfish” Turritopsis dohrnii really last forever, even with all this gunk slowly working its way into its cells and genomes?

I’m not convinced. Just because you can reverse your life cycle or clone yourself doesn’t mean you’ve got a get out of jail free card for all the consequences that come with being a living thing in the first place. You are still subject to that nasty gunk build up.  Some species like Hydra vulvaris may have evolved ways to clean this gunk and beat the system, but the jury is still out on how, and for how long. While the “immortal” jellyfish Turritopsis dohrnii may be able to turn back its life cycle, it may not escape the inevitable slowing down that comes with age. In other words, while reversing your fate and escaping death for a short while may be a neat trick, it doesn’t guarantee immortality.

Work Cited

[1] Stefano Piraino, Ferdinando Boero, Brigitte Aeschbach and Volker Schmid (1996). Reversing the Life Cycle: Medusae Transforming into Polyps and Cell Transdifferentiation in Turritopsis nutricula (Cnidaria, Hydrozoa). Biological Bulletin , Vol. 190, No. 3 (Jun., 1996), pp. 302-312

[2] Stefano Piraino, Ferdinando Boero, Brigitte Aeschbach and Volker Schmid (1996). Reversing the Life Cycle: Medusae Transforming into Polyps and Cell Transdifferentiation in Turritopsis nutricula (Cnidaria, Hydrozoa). Biological Bulletin vol. 190, no. 3  pp 302-312

[3] Martínez DE (1998). Mortality patterns suggest lack of senescence in hydra. Exp Gerontol. vol 33 no 3 pp 217-25.

[4] Ariel B. Lindner, Richard Madden, Alice Demarez, Eric J. Stewart and François Taddei (2008). Asymmetric segregation of protein aggregates is associated with cellular aging and rejuvenation. PNAS vol. 105 no. 8 pp 3076-3081 doi: 10.1073/pnas.0708931105

The post Are Jellyfish Immortal? first appeared on Deep Sea News.

A link from one of readers (thanks Ashley!) pointed us to a story on MSNBC about a very large Lion’s Mane jellyfish (Cyanea capillata) that broke apart and stung up to 100 people on a New Hampshire beach last Wednesday. Lion’s Manes can get very big, their bell can be over 3 feet. Their tentacles though are another story and quite intimidating! A small Lion’s Mane can have a tentacle trail 10 feet long. A much larger one may have over 150 tentacles trailing over 30 feet behind it!

So how can jellyfish sting if they break apart or are dead and washed up on the beach? The tiny stinging cells, called nematocysts, can be thought of like a mouse trap. One you set the mouse trap it only needs a trigger to do its damage. It doesn’t need any outside help to be maintain. It just has purpose, to sit and wait for an unfortunate victim to trigger the hard-wired response that millions of years of evolution have refined into a potent venom delivery system. Much the like the mouse trap, once set it does not let go easily.

From MSNBC/LiveScience writer Jeanna Bryner:

Though not a common occurrence, marine biologist Sean Colin says with such a large jellyfish, and so many trailing tentacles (not to mention those that break off in the water), the occurrence is feasible.

“It’s certainly not common, but it’s certainly in the realm of possibility, because they do have so many tentacles if they’re that large. If they’re broken up they could be all over the place,” said Colin who is at Roger Williams University in Bristol, R.I.

Profile of a giant
This species is typically found in the cooler regions of the Pacific Ocean, Atlantic Ocean, North Sea and Baltic Sea. And they rarely show up on this beach. “I haven’t seen anything like this in my life, said Brian Warburton, who has been with the New Hampshire State Parks department for six years.

All the action transpired in about 20 minutes, when Warburton and his colleagues administered first aid (vinegar treatment). “There wasn’t time to sit and measure this thing. We just got rid of it,” Warburton told LiveScience. “Think about a glob of Jell-O you’re trying to pick up with two hands,” he said, explaining the need for a pitchfork to pick it up.

Nematocysts are proteinaceous substances and are not living cells or organelles. They discharge extremely rapidly and work by building an immense amount of pressure inside the cell (up to 15 MPa or 2176 lbs/in²) by storing oodles of calcium ions. When discharged (see above), the ions are rapidly ejected into the surrounding cytoplasm, setting off the chain of events resulting in a painful sting. Research by Nüchter and colleagues measured the escape velocity and kinetics of nematocyst discharge in the freshwater hydrozoan, Hydra. The steps above took place during 700 nanoseconds, creating an acceleration of 5,410,000 g!

Not all nematocysts are filled with venom though, but it is not a chance you should be willing to take. Since the stinging cells matter not whether its creator is alive (at least over the shorter term, the protein does degrade rapidly), it still does a lot of damage on its own its always a good idea to approach a beach jellyfish with caution and your flippy-floppies on. Very important to make sure your kids know never to touch a jellyfish unless with a stick from a safe distance. As I tell my 3 children, jellyfish are pretty from a distance!

Nüchter, T., Benoit, M., Engel, U., Özbek, S., & Holstein, T. (2006). Nanosecond-scale kinetics of nematocyst discharge Current Biology, 16 (9) DOI: 10.1016/j.cub.2006.03.089

The post Jellyfish: Pretty from a Distance first appeared on Deep Sea News.