World Jellyfish Day Q & A

FIRST OF ALL, HOW

Well, if we’re going all the way back to the beginning, I guess we can lay the blame for how jellyfish did the thing primarily on the self-replicating RNA of the Eoarchaen, the REAL culprit of any and all issues regarding life on Earth.

Somewhere along the way, single-celled organisms organized into gangs, and that spiraled wildly out of control sometime in the Cambrian 500+MYA when they were like, “wow, radial symmetry is the next big thing” and the earliest known jellyfishes died tragically and were fossilized.

These fossils show species that are nearly identical in structure to many of the clades we see today. So, basically, what I’m saying is NOBODY AT ALL REALLY KNOWS HOW.

WHAT ARE THEY MADE OF? GRAPE JELLY? GHOSTS? ALIENS? ALL OF THE ABOVE???

All of these are excellent guesses, and have probably had some historical figure defining them as such at some point in human history. HOWEVER, they are made of neither ghosts, aliens, nor jelly; NOR ARE THEY FISH.

What they are is… mostly water. Really. Only about 5% of a jellyfish is actual solid matter. The main structure of the body has a thin epidermis lining the outside and a gastrodermis lining the inside, and everything in between is the mesoglea - a jelly-like (FINE, I GUESS THEY ARE JELLY) hydrostatic skeleton that has muscles, nerves, a basic immune system, and proteins like collagen for structure.

So, if you ever put a jellyfish on land (DON’T THOUGH, VERY RUDE) they end up just melting into a very thin layer of slime. That’s jellyfish: 5% slime, 95% water.

ARE THEY PLANKTON? DOES IT DEPEND ON THE SPECIES?

I have only now realized that many of these questions open up the very gooey can of worms that is the word “jellyfish”. To be clear: I use the term “jellyfish” to mean species that have a medusa life stage - that’s the life stage that most people recognize as a “jellyfish”. Medusae are present in a few classes within Cnidaria, but not all the species in these classes have medusae. Does that make sense? It’s very complicated and confusing.

So now that this is as clear as mud, if we’re using “jellyfish” to mean “cnidarians with adult medusae stage”, then YES they are planktonic. A plankton isn’t necessarily a microscopic organism - they can be large species, since the only defining factor is that they are passively pulled along by the current. Jellyfish can swim, of course, but are still largely at the whim of ocean currents.

It does also depend on the life stage - earlier stages of the jellyfish life cycle, the polyp/hydroid stage (think tiny sea anemone), are stuck to the ground like a tiny venomous tree, so they are not planktonic. Obviously. Listen, I SAID IT WAS COMPLICATED.

WHAT’S IT LIKE BEING A JELLYFISH?

Probably pretty wet and pretty chill, actually. Until a sea turtle finds you.

CAN JELLYFISH CHASE YOU DOWN? HUNT? ACTIVELY SEEK EACH OTHER OUT?

Okay listen so recently there was a paper published by Kaartvedt et al. called “Social behaviour in mesopelagic jellyfish” and they found that the helmet jellyfish Periphylla periphylla could actively seek out other members of its own species that were above them in the water, moving at FIVE TO TEN TIMES THEIR NORMAL SPEED TO CATCH UP. Not only that, THEY THEN TANGLE THEIR LIL ARMS TOGETHER AND IT’S! ADORABLE!!

The actual mechanism/function/purpose is unclear as of yet, but it’s still VERY COOL. Is it to facilitate hunting? Is it for mating? Is it some other third thing that is equally mundane? WHO KNOWS.

Anyway, jellyfish do have sensory organs called rhopalia, so they can take in information about their surroundings. They also have diffuse nerve nets throughout the body, and some have more centralized systems of nerves that are like a predecessor to the central nervous system (who’s brainless NOW, huh punks???) Still, jellyfish are more tactile predators - i.e. we see a notable response when prey physically touches a jellyfish. I can pretty much guarantee that they do not, in fact, use any of this for chasing down humans.

HOW MANY JELLYFISH COULD YOU TAKE IN A FIGHT

In the ocean, no rules, no protection: I could probably punch 100 evil jellyfish before succumbing to either a) box jellyfish venom, or b) anaphylaxis. An honorable death

On land, WWE stage, screaming crowd and me as a heel: I N F I N I T E

IS THE IMMORTAL JELLYFISH ACTUALLY IMMORTAL? ARE THERE OTHERS?

The immortal jellyfishes, Turritopsis spp., are arguably one of the most famous (infamous? maybe) jellyfish. It is because they are actually, for real, immortal.

Now, the definition of immortal in this case is probably not exactly how we, as humans, mean it. These jellies are immortal in a Benjamin Button kind of way - when stressed, injured, or otherwise in danger of dying, their tissues start degrading until all that remains is a tiny cyst-like ball that attaches to a surface. This cyst will then eventually regrow into a tiny hydroid - the first life stage of a jellyfish. Eventually this hydroid will metamorphose again into a free-swimming adult that is genetically identical to the original.

This has been seen in at least one other species - moon jellyfish have been known to grow polyps (their version of a hydroid) out of their adult body that can then “redo” the full life cycle as well. Not sure if we, as humans, would enjoy growing a baby out of your leg if you twisted your ankle, but I GUESS it works for some.

FAVOURITE AND LEAST FAVOURITE JELLYFISH

Favourite: Big fan of all weird and deep sea jellyfish. Deepstaria, Stygiomedusa, etc. Also flower hat jellies, fried egg jellies, sea nettles, firework jellies, generally all hydrozoans… OKAY YES IT’S ALL OF THEM

Least favourite: None of them, how dare you

IMPACTS OF INVASIVE AND INTRODUCED JELLYFISH

We’re seeing invasive jellyfish crop up all over the place - likely brought in via ships’ ballast water. Jellies as a whole are very resilient and spread very quickly when conditions are favourable. A couple good examples are the freshwater C. sowerbii invading a lot of North American lakes and rivers, and the various jellies that have started appearing in the Black Sea.

Regardless of what species or what location, invasive jellies can be hugely detrimental to an ecosystem that has never had them before. Jellies are very efficient predators - despite being mostly passive in their “hunting”, they clear out a lot of microscopic food sources as they grow. This limits how much food is available for other species; and, to add insult to injury, also limits the overall numbers of those species as their larvae, eggs, or juveniles are probably also fed on by the jellies.

WHEN WILL THEY TAKE OVER THE WORLD ALREADY??? I’M WAITING

Well, GOOD (?) NEWS my friend! Due to overfishing, global warming, and their general resilience to to all of the things going wrong with the environment lately - they already are!!!!

For real though, jellies are a good indicator of marine health - and since they are drastically overpopulating, it is a sign that things are very, very wrong (EVEN for us jellyfish fans, tragically).

**HOW DO JELLYFISH LIKE PANDEA RUBRA GET THEIR COLOUR? IS IT STRUCTURAL OR PIGMENTATION?**

There are a couple of different things that contribute to jellyfish coloration! The majority of jellies get their coloration from carotenoids and other pigments that are either picked up via prey or synthesized internally. I am not sure about specifically P. rubra - however, P. periphylla, a similarly vibrant red cnidarian, has pigmentation from porphyrins that spread through the body as it ages.

There are, of course, some jellies that are biolmuniescent - the most well-known being the crystal jellyfish, Aequoria victoria, which is the species from which the Green Fluorescent Protein was synthesized. As well, some jellies take up symbiotic algae known as zooxanthellae, which will also give them a blue/green/brown tinge as the case may be!

WHY ARE SOME SPECIES HARDER TO CARE FOR/PROPAGATE IN CAPTIVITY?

Just to make this easier, here is my very helpful diagram of Jellyfish Life Cycles

IN MY SPECIFIC EXPERIENCE, it all comes down to how “easy” it is for each stage to be reached. Some planula need specific things in order to settle; some polyps are just much slower to asexually reproduce into more polyps; some have very specific or slow-acting cues that limit how quickly they can strobilate; and some are just less hardy - so when you’re working with limited numbers already, one thing goes wrong and you wipe out your whole population of polyps.

An example of this is that with the right cues, A. aurita polyps can strobilate in 1-4 weeks, whereas the wait for C. fuscescens polyp strobilation can last 5-8 months. AGGRAVATING.

WHAT’S UP WITH THAT JELLYFISH ANIME

I have no idea but one day someone showed up at my job dressed as a jellyfish princess that I assume was from it and it was an EXTREMELY good day.

CAN WE EAT JELLYFISH AND ALSO WHY DON’T WE?

We can, and we do! Several species of jellyfish are edible, and are widely consumed in Chinese and many Southeast Asian cuisines. It is primarily used for the texture - jellyfish as a whole is salty (obviously), but also tends to take on the flavour of whatever it is cooked in. They are served dried, pickled, marinated - the list goes on.

They’re a very good alternative to the more traditional… um… marine options, especially since fish stocks are collapsing and jellyfish numbers are skyrocketing. Even I, noted jellyfish lover, have tried eating marinated jellyfish. I super didn’t like it (IT JUST FEELS LIKE A JELLYFISH, I WAS VERY AWARE OF WHAT I WAS EATING) but I will absolutely be on the bandwagon for switching in the name of sustainability.

JELLYFISH STING YOU WITH ELECTRICITY?

A jellyfish sting is actually a VENOM! Like a bee sting, a snake bite, or an assassin leaping down on you in a dark alley at midnight with specialized needle-gloves filled with a neurotoxin, catching you by surprise when you were just trying to get home from your job as a business magnate with lots of enemies (technically a venom, don’t @ me).

The sting comes from millions of microscopic cells called cnidae, which are basically just a tiny, spring-loaded and venom-filled harpoon in a bag. When you brush up against a jellyfish, these discharge, and voila! You are now the proud owner of jellyfish venom coursing through your veins.

SO I JUST PEE ON THEM OR WHAT

Guys. Friends. Listen. I care about you. Please don’t pee on your jellyfish-stung friends. Unless you’re into that, everyone involved has consented, and there are actually no jellyfish present. PLEASE.

DISCLAIMER: IF YOU GET STUNG BY A JELLYFISH AND YOU DON’T KNOW WHAT SPECIES IT IS, GO TO A HOSPITAL. I AM NOT A MEDICAL DOCTOR AND SOME JELLYFISH DON’T HECK AROUND.

That being said, if you are stung by a non-lethal jellyfish: DON’T PEE ON IT. When you touch a jellyfish, a bunch of the aforementioned cnidae discharge into you, and sting you. However, a lot of cnidae also end up on you, undischarged. If you pee on that, or rinse it in freshwater, or a whole bunch of other things – that actually causes those undischarged cnidae to go off. So, it will actually make your sting worse.

The best way to topically treat a jellyfish sting is to rinse it in vinegar, and then hot water. Vinegar is a fixative, and it causes the cnidae cells to swell up and become nonfunctional. Any old store-bought vinegar is fine (but don’t dilute it) and don’t then dunk you fries on your arm or whatever afterwards even though you’ll smell delicious.

You’ll likely still be itchy or uncomfortable afterwards, so from PERSONAL EXPERIENCE I recommend any topical anti-itch cream (Gold Bond, hydrocortisone, etc).

SOPHIE STING INDEX OF JELLYFISH THAT SHE HAS BEEN STUNG BY, RANKED

I actually haven’t been stung by that many species so this will be a short list

LION’S MANE (“OW. VERY OW”)
PACIFIC SEA NETTLE (“oooh ow why did I do that”)
ATLANTIC SEA NETTLE (“OW”)
AUSTRALIAN SPOTTED JELLYFISH (“oW”)
SPOTTED JELLYFISH (“… ow”)
UPSIDE DOWN JELLYFISH (“…………it’s f i n e”)
MOON JELLYFISH (four hours later “WHY AM I SO ITCHY”)

I DEMAND JELLY SECRETS!

I have revealed all of them. There are no jellyfish secrets left. Not even the one about how moon jellyfish and box jellyfish are as genetically different as humans and sea urchins. Or that the smallest jellyfish is a miniscule hydrozoan that creeps along the sea floor and is only a few millimeters wide. Or the one where there’s a jellyfish called a by-the-wind sailor, V. velella, that has a tiny rigid sail on the top of its bell that it uses to cruise along the water’s surface. Or that man-o-wars aren’t actually single jellyfish, but a colony of hydozoans th͘at͜ ̨h̷av̛e̕ ͝e͜volved tog͢et͠h̶èŕ to͝ be̵c͡ome di͝ff̕ȩre̵n͞t ̨p҉art͏s̛ o͏f a ̶s͜i̵ng͢l͘e͢ bo̡d͜ỳ l̛͟͢i̷̧k̀e̴ ̷̧͜g̢̨͜o̡n͏̧͘a҉d̵́s,̡͡͝ ̶͠f͝e̷ę̵͞d̶̨i̶͢͢ng͢ ̡̛a̷r̸̡m̢s̵͏,̶̵͢ a҉̵̵ ̶̨͜͞͝p̵̢̛͘ò̵o̶͘f̨͘ý̶̵ ̴͘f̀́͟͞l̢͟͞ó̶̕á́͢ţ̴̡͡,̴̴̕ ̷̡͘͢o̴͝r̢̀͡-̢҉҉̵ ̵̡d̛́͘̕͝ó͘ ̶̢̕n̛͞o̷̷̸͢͠t̶̀͢ ̶̨̕ŕ̀͏̶é́̕͢͜v̶͟͢e̵a̸͞͝l̸̢̀͝ ̀͏̷͟t͠͏̶̵͜h̕͡e̢͠ ̴͢j̢̀e̴̢̨̨͝l͟͜͡l͜͝y̡̕͠f̀͜͟͝͡i̷̧͘s̶̢͡͠҉h́́ ̷͞s̀̕e̶͢͠c͜r̸̴̶̸͜e̸͘̕҉́t̷͝͝s͢͢ ͏̴̢͜͢D̶͞҉̘͕̭͖̦̙͎̠͕͓͠O̴̶̳͇̺̩̦̱͔̝̩͇̼͢ ͏̡͙̠͚͉͖̟̤͙̯̹͘N̢͞҉̮̺̘͢ͅO̶͏̤̱̟͓̳͍͙̰͖̘̗̙̣̺̜͎̕͢͢Ṯ̨̻͉͍̙́͜ ͘͜͝͞҉̟̟̫̬̘̼̯̣͇̟̜͇̟ͅR̝̪͔͕̠̝̖̝̞͉̗̥͎̲̠̥̕͡͝ͅȨ̡̟͎̹͈̠̜̖̗̱̮̻͔͠V̷̸͏̲͈̪̯͔͕͕͈̝͈̫̣̰E̷̶̤̠̩̩À̮̻͔͔̬͙̰͍͠͝L̸̨̡̛̹͖̖͔̹͈͖̖̖͇̬̯ ̸̡̯̱̝̖͉̰͎̀͞͡Ṯ̷͓͙̩̥͟ͅH͏̸̨̥̲͉̹̯͎̲̟͎͝Ę̶̸̟̼̩̮̕ ̶̡̯̮̯̯̞̮̰̻͚͜͜J̦͔̲̰͜͟͜E̸̡͇̤̩̣͔͈̙̺̝̹̮͍͚̣̳͞Ĺ̗͕͍̲͔͇̘̰̹͈͞ͅĹ͙̹̠̟̦̺͉̩͓̹͍̺̠̫̦̱̤́̕Y̢̹̘̰̹̦̜̤̬͕̫̘͇̼͈͍̹̣͜F̶̵̕҉̶̞̙͙̩̳̖I̷̴̙̳͉̘͍͕͇̗͈̮͉̲Ś̳̩͉͘͟͟͜ͅH͔̤͔̲̩͖͘͢͢ ̛̦̼̤̠͈̝̝́͘͟S̸̢͘͜҉̦̹̺ͅͅE͞҉͖͕̹̰͔̠̪͖̙͓̪̲̟̱̕C҉̶͎͈̲̞̮̤Ŗ͖̬͖̗̬͎̱̠̥̥ͅE̢̘̖͕̻͉̪̬͍̣͙͜͜͝ͅT̛͓̻̝͖͓̗͓͙̠̗̺S̵̵̘̠͕̝̺̩