jellyfish coloring page

All About Jellyfish

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Hey there, this is Color and Chill with Yvonne Page Illustrates and you’re watching Facts to Relax, the segment where I research a topic I find interesting and want to learn more about and then share my newfound knowledge with you, while painting a picture on the screen. If this sounds like something you might be into, I suggest subscribing to this channel so that you can learn new, random facts along with me while we relax together. I’m also on Instagram where I summarize some of my favorite bits from each episode in easy to understand quick cards, so follow me there too if you’re in the neighborhood. And if there’s a particular subject you want me to research and make a video about, let me know in the comments below!

So, today’s episode is all about jellyfish. We’ll talk about where jellyfish live, what they’re made of and what they’re all about, how they spend their time, and how they manage to wreak havoc in many different ways. We’ll look at jellyfish reproduction, bioluminescence, and what happens when they’re sent into outer space. We’ll also talk about their stings and whether or not peeing on a sting will help ease the pain. I put some of the topics we’ll cover with timecodes in the description below, just in case you want to skip  around and find out something specific, but otherwise, let’s settle down somewhere comfy, take a deep breath in and then let it out again slowly as we relax and get to know one of the oldest living species on earth-the jellyfish.

Jellyfish, sometimes referred to as jellies or medusas, are a type of marine invertebrate, meaning they live in the ocean and have no backbones. More specifically though, they have no bones at all. They’re just these gelatinous masses pulsing around, eating small fish, shrimp, fish eggs, and plants, looking lovely, and occasionally stinging people. The live in oceans all over the world and can be found in pretty much every type of ocean water: warm and tropical or cold and Arctic. Additionally, they can be found near the surface of the water but also, at the bottom of the ocean. And to be completely transparent, I want to mention that though most jellies live in the ocean, some, like Golden Jellyfish can be found in saltwater lakes, and others even can be found in freshwater lakes. Jellyfish DGAF. They will not conform to our human-made concepts of what a jellyfish should be, where a jellyfish should live, or even what a jellyfish should look like. They do what they do and they really don’t care how we feel about it. Actually, that may be giving them too much credit since jellyfish don’t actually have brains or hearts either so they neither care, nor think about anything really.

Though jellyfish live in the water and have fish in their names, they aren’t actually fish, so let’s just get that straight from the get-go. They’re not made out of jelly either, in case you were wondering. Technically speaking, jellyfish are members of the phylum Cnidaria. With about 3,000 different types of jellies identified, and probably another 30,000 or so species not yet identified but suspected to exist, scientists like to refer to the group fondly as “gelatinous zooplankton.” Plankton are marine drifters, broken up into two different classes: phytoplankton which are plants, and zooplankton, which are animals. Basically, zooplankton are any weakly swimming or floating sea animals that drift along with water currents and make up the food supply for other oceanic organisms. 

So, if jellyfish are a food source for oceanic creatures, which ones eat them? Low on the nutrient scale, jellyfish are like the potato chips of the sea. Plentiful and delicious. Well, I can only assume they’re delicious because leatherback turtles, penguins, albatross, tuna, crabs, and even ducks enjoy them. They’re easily digested, on account of their lack of bones and pretty easy to catch. As climate change has devastated the earth’s oceans and the marine life they contain, jellyfish are one of the few creatures that have actually thrived amid the changes. As they become more plentiful and other, more desirable food sources have become less available, many sea creatures and birds have had to adapt to eating jellies. A not-so-great side effect of this has been that, besides not being a particularly nutritious meal, jellyfish and plastic shopping bags floating around in the ocean look a lot alike and some animals, like sea turtles, have been seen accidentally eating plastic shopping bags instead of jellyfish. Not ideal since consuming too much plastic can kill these beautiful reptiles.

Sea creatures aren’t the only ones who eat jellyfish however. Even humans have found ways to enjoy them. About 25-30 species of jellyfish are known to be edible to humans and are low-calorie, low-fat, containing just bit of omega-3 and 6 unsaturated fatty acids, and protein and collagen rich. I checked the NOOM app for any of you dieters out there, and jellyfish is rated as a “yellow” food. Recipes on the internet suggest shredding or slicing raw jellies thinly and tossing them with sugar, soy sauce, or other dressings in a salad or, boiled and served with veggies. Described as having a “delicate and mild flavor,” somewhat salty and chewy, jellyfish are probably a pretty acquired taste, though they’ve been part of Chinese and Japanese cuisines for a very long time. Personally, as someone who doesn’t like seafood, I’ll be avoiding eating them if at all possible as they become a more popular fine-dining option in the West. That being said, as jellyfish populations grow and other seafood options decrease, they really might become the next big thing in the world of culinary seafood delicacies. Jellyfish rolls instead of lobster rolls? Jellyfish sushi? Maybe even battered and fried as an alternative to calamari. The possibilities are endless!

So, it’s believed that jellyfish have been around for at least 500 million years, making them the oldest living multicellular animals on the planet. To compare, dinosaurs were roaming the earth between about 245 and 66 million years ago, and by all accounts, humans have only been around for about 200,000 years. Let’s let that sink in for a minute. Jellyfish are twice as old as the earliest dinosaur! It’s hard to find fossils of jellyfish since they have no bones but in 2007, several nicely preserved fossils from about 505 million years ago were found in the US state of Utah, with prominent umbrellas and trailing tentacle shapes, leading scientists to conclude that they were from some sort of prehistoric jellyfish…which honestly don’t seem much to be that much different from modern day jellyfish. I’ll include a link in the description below to the journal pages that includes photos of the fossils because they’re quite interesting to look at. Considering this find, it’s notable to say that jellyfish have managed to not only survive every global change or disaster that has caused mass extinction of other species but also, they seem to thrive through it all. In fact, as I mentioned a few minutes ago, while other marine life is suffering due to the current climate change issues, jellyfish are out there living their best lives right now. They appear to really appreciate the rising temperatures in the oceans and remain highly unbothered by the decreasing oxygen levels in the water. Additionally, since some of the predators, like tuna and swordfish have declined in numbers, they seemingly have nothing to stop them from multiplying quite rapidly, and in some areas, to the point that it could be considered to be an overpopulation of jellyfish. 

Now, before we rejoice over the fact that at least there’s one creature out there that seems to be thriving and NOT on the brink of extinction thanks to us humans, an excess of stinging water balloons isn’t quite as ideal as one might think and here’s why. 

First of all, they keep showing up in places they don’t belong and wreaking havoc, usually just because of their sheer number more than any intentional wrong-doing on their parts. Remember, they have no brains to think up their evil plans, they just accidentally keep getting themselves into bad situations, much like myself in my early teen years. For instance, in 1999, Manilla, the capital of the Philippines, experienced a blackout due to a large number of jellyfish being sucked up into the seawater intake of a major power plant in the area, clogging the mechanism and about fifty truckloads of jellyfish had to be removed. In 2006, the USS Ronald Reagan, a nuclear-powered aircraft carrier, had the cooling pipes of the ship’s nuclear reactor clogged by blubber jellyfish, near Brisbane, Australia. And, in 2011, not one but BOTH reactors in the Torness Power Plant in Scotland had to be shut down temporarily when jellyfish obstructed the cooling water filters. These are just a few examples of many showing how extinction of species isn’t the only way life on earth can be affected when Mother Natures’ not pleased with our behavior.

Now, there are many different types of jellyfish but there’s one thing that they all have in common. The main body of a jellyfish looks like a bell or an umbrella top. This is made up with two layers of cells called mesoglea with a non-living watery substance between them. In fact, they’re made up of between 85 and 98% water. When they wash up onto beaches, they basically melt into the sand and disappear as their water evaporates. Their bell shaped design allows them to grow larger and eat more without needing to have a high metabolism. Muscles in the bell contract, squirting water in the opposite direction from where they want to go and push them along in the oceans. Sometimes though, they just let the ebb and flow of the tides carry them along. Some jellyfish swim with their bells up and others with their bells down. Bell sizes can range from a diameter of two-tenths of an inch to over six and a half feet. Even more varied, they can weigh anywhere from under an ounce to about 440 pounds! 

Jellyfish bells contain their stomachs but they lack hearts, lungs, and brains. Though they’re about as evolutionarily distant from humans as is possible, they have evolved to get the things they need just like the rest of us. For example, jellies can’t breathe so they absorb oxygen right through their thin skin. Without a heart, they also don’t have blood coursing through veins and they use a nerve net, just below the outer layer of their skin to receive signals about any changes in their environment, negating any need for a brain. One of the greatest things about not having a central nervous system means that jellyfish can’t feel pain, either physical or the emotional pain of knowing that one of your brothers just got sucked into a nuclear engine. A few types of jellyfish, like the Beroid comb jellyfish have hundreds of rows of teeth that they use to grab onto prey and pull them into their stomachs but most species are toothless. Jellies hunt their prey by letting their tentacles drift or sink through the water or by forming spiral tentacle traps, and then stinging and debilitating their prey and bringing it up to their mouth holes. 

Now listen, we already know that jellyfish are biologically simple creatures so it shouldn’t come as much of a surprise to find out that most eat and poop from the same orifice, found at the base of the bell. Of course, without complex digestive systems, their poop doesn’t look much different than when it went in. Basically, they trap the food in the stomach pouch inside the bell, absorb nutrients from it and then release the rest back out the way it entered. Yeah. They poop through their mouths. Or, if that’s too gross, if you want, we can think of it like jellyfish don’t poop at all…they just eat and then spit what they don’t need back out. Yes, let’s think of it like that. That’s way less disgusting. One notable exception to that rule is the Irukandji jellyfish that we’ll talk more about in a few minutes, who poop out of the base of their tentacles, essentially meaning that this species has one mouth and four butts.

Upside-down jellyfish, the ones who float around with their bells under their tentacles may live on the seafloor in tropical waters while microscopic algae grow on their tissues. The algae are able to use the sunlight on these basking jellies to grow and then the jellyfish are able to use the algae as a source of nutrition.

Jellyfish don’t have ears, though they do have sensors that help them detect up and down but not sound waves, and they certainly can’t hear in the same manner that we do. Likewise, though they have little sensors that help them detect light and dark, most don’t have what we would consider eyes. But, when they go big, they go all the way big because one group of jellies, the box jelly, not only has eyes with corneas, retinas, and lenses, much like our own, they have twenty-four of them. They take the art of having eyes to a whole new level, with four different types of eyes, with one set of upper lens eyes which can see through the water’s surface and into the space above, making it easier for them to navigate up towards mangrove trees above the water’s surface. Now two things to note here- box jellies are quite deadly to both animals and humans if stung and they’re also basically see through. So, you might just be sitting there, minding your own business, splashing around in the water one day and then all of a sudden you just see twenty-four tiny eyeballs floating towards you and you’re like “wow, that’s the weirdest thing I’ve ever seen” and then BAM, you’re stung and maybe even dead. Sorry pal, what a not-ideal way to go.

Anyways, most, but not all jellyfish have tentacles hanging from their bells. The tentacles are the parts of the jellies that sting. The size, shape, and number of tentacles vary between species, with some looking like stubby little legs and others that are long and elegant and flowing. Even when they’re long, jellyfish never get their tentacles twisted or knotted up and they never accidentally sting themselves. They can sting jellyfish from other species though. The super large Lion’s Mane jelly can have tentacles that are even longer than a blue whale, which is the biggest mammal on earth. The cells on their tentacles are called “cnidocytes,” (niy-dough-sights) and they literally explode and shoot out tiny barbed, venomous harpoons called nematocysts when touched. This helps stun and paralyze their prey so they can eat them but unfortunately, even though they don’t mean to harm humans since they can’t eat us, we often find ourselves accidental victims. Approximately 150 million jellyfish stings are reported worldwide each year. Though stings from some species can be deadly, others barely register, though this has nothing to do with the size of the jellyfish. In fact, the Irukandji, the same ones who poop through their tentacles, are the smallest of the jellyfish species at only about a cubic centimeter in dimension, but they’re also one of the most venomous. The pain from their stings almost always results in a hospital visit and heavy doses of pain killers, as it can last for around twelve hours and cause victims to beg for death or actually attempt suicide to relieve themselves from the suffering. It’s that bad.

Most jellyfish stings however, while painful, normally can be relieved with less extreme treatments. One old wives’ tale that you may have heard of for jellyfish stings is to have someone pee on the affected area but that normally doesn’t work and may make it worse. Rubbing the area with sand or pouring alcohol, hydrogen peroxide, or ammonia are also ineffective. Vinegar may help but not always so it’s better to instead focus on removing any remaining tentacles embedded in the skin with your fingertips and rinsing the area with warm water, preferably the sea water since plain, unsalted water may make the pain worse. Continue to monitor the area for any signs of severe reactions. Keep in mind that even dead jellyfish can sting so you should maintain caution if you see any washed up on a beach and keep an eye out for any detached tentacles that may be lying around. Since most jellyfish predators are immune to their stings, they may be safe but if you eat something that ate a jellyfish but didn’t fully digest it, like a squid for instance, you can still end up being stung. Ouch! Interestingly though, some other sea creatures have learned how to utilize the jellyfish’s dangerous tentacles, such as octopuses, who are known to hold fragments of jellyfish tentacles with their sucker arms and use them as weapons.

A group of jellyfish is called a “bloom,” or a “swarm,” or a “smack” and it’s believed when they congregate in groups, it’s usually for purposes of reproduction. Because jellyfish don’t make babies the way we do with one male and one female working together. Oh no, their approach is quite different. When it comes to reproduction of jellyfish, there are two possible options. In a few species, females will receive sperm male jellyfish have released in the water into their bells to fertilize eggs inside but more commonly, both male and female jellyfish adults simply release their sperm and eggs into the water around them to mix and grow there and hope for the best. As random sperm and eggs combine in the water, they form a planula, which is a free-swimming larva that looks like a little flatworm and this is like the infant stage of a jellyfish’s life. The planulae settle on rocks and form polyps, which would be considered their “childhood.” Eventually, when conditions are ideal, the polyps will begin to clone themselves asexually, meaning without help from any other jellyfish in a process known as strobilation. The strobilating polyp is called a scyphistoma. This process begins with the polyp’s tentacles being reabsorbed into its body and the body itself becoming narrower while visible segments begin to form. Eventually, the segments separate and float off to become an ephyra, which is like the teenage equivalent of a jellyfish. They don’t have closed bell shapes or stinging tentacles yet, but they eat and grow a ton until they reach the adult medusa jellyfish stage of life. Initially, the medusa may be smaller than its final size but it’s mature and ready to reproduce if it needs to. At this point, depending on the species and where they live, they will continue to grow as large as possible, as quickly as possible, since the larger they are, the better they can reproduce and detract prey. So, if there are multiple clones of any single jellyfish, how do they make sure they don’t mate with themselves? Well, the original egg and all its future clones are of the same sex, either all males or all females so reproduction among clones is impossible. The adult, medusa stage of life serves mainly to reproduce and most jellyfish won’t live much longer than it takes to do so and they generally reach old age pretty quickly. In fact, jellyfish are apparently very good at identifying ideal conditions for reproduction so they don’t have to live incredibly long and boring lives. 

Jellyfish lifespans can vary between a few hours and a few years. The Turritopsis dohrnii, however, is basically immortal, since instead of dying from old age, it can transform itself back into a colony of polyps at will. Then, the polyps spawn new, genetically identical jellyfish clones from those polyps and grow to maturity again. Even if it gets injured or begins to starve, the Turritopsis dohrnii can just transform back into a polyp. This process is called transdifferentiation. They aren’t, of course, immune to being eaten by predators however, so they’re not completely immortal. Additionally, many adult jellyfish of all species have immature polyp clones still living on the sea floor, able to asexually create even more clones long after a mature medusa with the same DNA has died. In that sense, any jellyfish can theoretically live a very long life. 

Many deep sea creatures, including approximately half of all jellyfish species utilize a chemical process called bioluminescence to make themselves glow in the dark. The way this works is that a substance called luciferin reacts with oxygen, releases energy, and light is emitted. Some organisms produce their own luciferin and others acquire it through their diets, i.e. by eating other smaller animals that produce their own. Many jellyfish get their luciferin from the small, bioluminescent crustaceans they eat. Bioluminescence in the deep, incredibly dark depths of the ocean can help sea creatures attract mates, detect and lure prey, fend off predators by scaring them with their lights or distracting them while they escape, or camouflaging into the area around them. I’m going to link to a few videos in the description below that show different examples of jellyfish bioluminescence. It’s incredibly cool to see as they don’t just light up like a lightbulb but may also pulse lights, and produce a rainbow of colored lights. Even more cool, in 2008, three scientists were awarded a Nobel Prize in Chemistry for “the discovery of the green fluorescent protein or GFP” thanks to help from the crystal jellyfish. After painstakingly isolating GFP from hundreds of thousands of crystal jellies, they were able to express and develop a palette of fluorescent proteins that can be used for many different applications, such as tracking the processes of insulin production, HIV infection, and muscle structure.

  In another impressive contribution to science, in 1991, 2,478 moonfish jellyfish polyps were sent into outer space on the Space Shuttle Columbia within flasks and bags filled with artificial seawater so scientists could examine the effects of microgravity on them. While in space, the jellies reproduced rapidly and by the time they got back to earth, there were more than 60,000 of them. And interestingly enough, these space-born jellyfish were, in fact, affected by the new, stronger gravitational pull they experienced on earth. They had difficulty pulsing and moved abnormally compared to their counterparts who’d been born on earth. Though we have very little in common biologically with jellyfish, we do orientate ourselves according to gravity much in the same way they do, indicating that if a human being were to be born in outer space and then brought down to earth, they would likely have similar issues and experience massive vertigo, the phenomenon which causes dizziness, spinning, and a feeling of being off-balance. Knowing this could alter how we handle space travel in the future.

As we end this episode of Facts to Relax, I hope that you’ve found this new information about jellyfish useful, or at least interesting. Don’t forget to subscribe to this channel if you want to learn more, random information along with me and let me know in the comments below what else you’d like me to research or, if there’s something important about jellyfish that you think I missed, share that as well. As always, thank you for taking time out of your day to stop by to color and chill with me. Bye.