True Facts: How Jellyfish Hunt

This episode is sponsored by Imprint. When the life of a jellyfish begins, it's not long before the sea monkeys start getting nervous. Fertilized egg, a few rounds of cell division, and they can already start moving around. Find a nice spot to settle and grow into a gelatinous tree, with arms that seem to be flipping the world off in every direction. And they can get away with that too, because they're armed. Get it? Because at just a couple weeks old, the polyps of jellyfish and other members of the cnidarian gang, like anemones and coral, have the ability to sting. Now if you had sea monkeys growing up, this might be a tough episode for you. If you look a little closer at those tentacles, you can see they can fire off what sometimes looks like weaponized pubic hair. These structures, nematocysts, aren't really designed to just shoot off willy-nilly into the water like this. Normally, they go off on contact. They have these little trigger hairs that, if touched, cause water to rush into the cell. And this creates an incredible amount of pressure. 150 atmospheres or over 2,000 psi. Now see all that stuff that's curled up inside? Well, it's like an innie belly button on steroids. All that pressure forces this inverted tube to rapidly turn itself right side out. It's like if you threw up so hard your esophagus came out. This first bit here is designed to pierce whatever touched it. And that allows the skinny part of the tube to unfurl inside the victim. And the whole thing has barbs all over it, and there's venom on it. Looks like the devil's dental floss. In any case, it makes these polyps great at catching sea monkeys, and digesting what they can, and discarding their carcasses like peanut shells on the floor of a ground round. Rest in peace. Delicious. But listen, it's gotta eat, because this jellyfish baby is actually a jellyfish babies. It goes through a transformation where it becomes a sort of ribbed-for-pleasure version of itself. What's actually going on here is that it's creating a clone army. A stack of genetically identical jellyfish saucer babies. And one by one, those get sent off into the world. Look at that, it looks like the stack is waving goodbye to itself. Now these look like cute little snowflakes, ringed with, well, sort of looks like camel toes. I mean, I don't mean... Well, anyway, they're cute. And you can start to see the jellyfish in them. Tentacles start to sprout along the outside, and the bell shape of their body starts to form. Gently pulsating, as if it were the fringe of a skirt on a ballerina. Of death. Look at this little toddler, for example. The red one. Adorable, right? No, he's a biter. Every kindergartener has one. You'll see. That tube hanging down in the middle there is its mouth-slash-anus. Or anus-slash-mouth. Either way, it's a classic chicken-and-the-egg sort of thing. Except, you know, a mouth and an anus. Poor little Timmy there is not going to be on the bus for drop-off, I'll tell you that much. You'll notice at this stage they can be a little twitchy. I mean, they do have to practice their swimming. And you might think that after half a million or so full-bodied crunches, they'd be ripped by the time they were grown. But no, they keep their renaissance figure as they get their bell on, and grow out those tenties. I mean, to be honest, they don't have that much muscle to work with in the first place. It's less than 1% of their body mass, compared to the 50% for most fish-butt. Sorry, for most fish. But in terms of the energy used to swim, fish are just fissioned. Jellyfish are jelly-efficient. It's terrible. They move through the interplay of two types of muscles. One type goes rouncies, and the other sort goes upsie-downsies. You can see the two types very well on this one. Looks like a macrame project on an acid trip. When a jelly like this wants to move, those muscles work together to contract the bell and squirt water out the back. Then to open back up, all they got to do is relax. And that's because its body acts like a spring that wants to return to its original shape. But this isn't just some flapping about. It's quite a precise movement that generates propulsion by farting out water donuts. The science hippies call them vortex rings. How lame is that? So these are rings of swirling water. And the way they swirl causes water to shoot down through the center. And if you see any water moving down, you know there's an equal force pushing up on the jelly. It's like looking at complicated footprints. Now to create the best swirlies, they need their bodies to be just the right stiffness. Not so stiff that it's hard to squeeze, but stiff enough so that it retakes its shape quickly, but not too quickly. Think Goldilocks, but with a stiffy. Or don't. To turn, they can do a little flippy wave thing around the edge of their bell. You can see it changes the water flow and causes them to rotate. But maybe the neatest part of this motion isn't the squeezing. It's in that relaxing phase. You notice that water rushes in as the bell expands. And this pushes the jelly forward, in a sense recapturing some of the energy it spent on flexing. But this is a two-for-one, because that water is also bringing food right to its mouth. Slash anus. It's either a stream of snacks or a bidet. Win-win. And that's why you see so many jellyfish flapping around all the time. They're not lost. Oh, they're eating. Jerry, that's a plastic bag. All right, honest mistake. You know what I get? I get jellyfish brain. It's what happens when you scroll through that mindless ocean of timelines on your phone. Sort of feels like how this looks. Now imprint gives you a better way to use that time. It's a fun and, quite frankly, beautiful way to learn. It's highly visual, bite-sized, and interactive. And it even makes sure that your brain holds on to what it's learning. No more jellyfish brain. I mean, there's a ton of things to choose from. Leadership, finance, philosophy, history. And look at this. Interpersonal dynamics. The psychology of human relationships. We could all use a bit of polish on that subject nowadays. And that's one of many multi-day courses you can take. You can go at your own pace, but if you just put in five minutes a day, you can get through a whole course in two weeks. And this is what imprint is great at. Helping you build up a habit around learning using the science of learning. There's a reason imprint was Google's app of the year and named essential education app by Apple. If you want to support this channel and be introduced to an excellent learning experience, you should check it out. Click on the link in the description and go to imprintapp.com slash ZeFrank. You'll get a seven-day free trial. And if you love it, which you will, a 20% off annual membership. Get imprint and make the most of your screen time. Don't get jellyfish brain. Where were we? Oh, right. One sort of jellyfish got tired of all this swimming around. The subtle but genius innovation of the upside down jellyfish was to turn upside down. And after that, it was off to the races. From that position, they've figured out a different way of creating those water flows to bring particles to its mouth. But you've probably noticed there's a whole bunch of other crap surrounding that mouth. That whole floppy cauliflower situation? Those are called oral arms. It's a good title for a war-themed pornography film, tell you what. Lots of jellyfish have them. They're not tentacles. These skinny bits here, they're the tentacles. The frilly ones are the oral arms. And while we're pointing things out, I should mention that these here are gonads. Because jellies don't give a f**k. Not gonna try and hide the gonads. No, they're gonna accessorize with them. Wear them like a brooch. For everyone to see, you could learn a lot from a jellyfish. Well, not that. I don't recommend that. Last thing I need is to get a call from your mom because you've stapled your gonads to your lapel like it's my fault. It's bulls**t. Anyway, the oral arms help capture and transfer food back to the mouth. From there, the bits go into a stomach situation and then into a network of tubes. And the tubes let all the parts get the nutrients and then it's back out again through the anus-slash-mouth. There are exceptions. Some have many mouths and many anuses like they were designed by AI with an NSFW prompt. But generally, jellies follow the classic, dare I say, timeless mouth-slash-anus-often-with-oral-arms paradigm. Simple enough. Anywho, the oral arms of the upside-down jelly are special in a couple of ways. One is that they incorporate photosynthetic algae into their tissue and then eat some of the food that the algae makes from light. The other is grenades. Oral arms are often equipped with stinging cells. That's what the little white dots are. But the upside-down jellyfishes go beyond. They release a mucus that contains what are called These cassiosomes have cilia on them and they can move on their own. But their surface is also jam-packed with those stinging nematocysts. And if a sea monkey has the gumption to rub shoulders with one, it's all over. Jerry, there's a pube on the slide again. But it's not mine. Look what happens when you add a whole bunch of sea monkeys to a swimming pool full of upside-down jellyfish mucus. And at first, it seems fine. But just one minute later, it looks like... Well, it looks like the sea monkeys I kept as a child. I mean, it's no wonder that some crabs wear these things as hats. I mean, it's stylish and no one's gonna mess with your head if it's covered with ouch-flavored pop rocks. But crabs aren't the only... Jerry, but crabs aren't the only animal known to associate with jellyfish. Juvenile jackfish, for example, will sometimes swim around with the jellyfish in its mouth. I don't really know how it avoids the sting. I asked one and it said... I'm sorry. Anyway, as they get older, it gets awkward. It's like that man who had a relationship with a volleyball in that beach movie, Castaway. Oh, and to whoever it is that names the fish, there's that fish whose actual scientific name is Boops Boops. Well, you should have saved that name for this one. Makes some sense for once. Anyway, there's over a hundred species of fish that associate with jellyfish. I mean, come on, you swim behind one of these things for a while. Tell me you wouldn't want to take a turn inside. That's what this one did. You get to use them for protection and maybe have a nibble once in a while. Because for some fish, the jellies are sort of like a gingerbread house surrounded by a thicket of stinging nettles. I mean, it doesn't always go so well. You know, mess with your balls, you get horny. Jerry, it's mess with the bull, you get the horns. Yes, I'm sure. Anyway, you can see that at least some jellies have a taste for sushi. The box jellyfish, for example, seems to actively hunt for fish using vision. I know it sounds like a stretch, but many jellyfish have these structures called ropalia on the margins of their bell. The moon jelly, for example, has eight of them and each ropalium contained two simple eyes. It looks a bit, you know, let's just say it puts the eye in vagina, so to speak. Subtle. Now, box jellyfish in the genus Trepidalium have four ropalia. Each one is on the end of a little stalk and contains six eyes. Four of them are simple things, but two of them are proper image-forming eyes. I mean, they look like real eyes. Each one of these little eye clusters has a crystal in it and this crystal acts like a weight. So no matter what direction the jelly is turned, one eye is facing up. And that's because they live in these water channels that go through mangroves. And they seem to be able to navigate to better hunting grounds by looking up at the canopy where it can detect changes in the lighting. It's sort of like if Street View looked like this. Now, the box jellyfish is called a box jellyfish because it vaguely resembles a box. And that's great. Call them what they look like. But be consistent. Like this one's not called a bag of dicks jellyfish. Should be. You call this one shrinkage and be done with it. But don't let the looks fool you. Here's a skeleton shrimp about to make that mistake. It's a real killer, this Lucernaria quadricornis. More like zombie dildo with pom-poms of death. Or what the Hogwarts sorting hat looks like when it's naked. You know what this one looks like? Looks like a French beret trying to steal some bok choy. It's the kite your dentist brings to the park. It's like if a hand reached up out of a clogged toilet. It's what a camping tent looks like when you let the kids set it up. It's an off-brand diva cup. If Cupid's bow was an automatic. It's the walk of shame after a ball gown had a fun night out with a paper shredder. It's a commemorative Stonehenge hat. Or a Spike Brero. A rogue placenta. If an acorn were a root vegetable. Or it's a gummy bear. If they were all shaped like butt plugs. When your ball stretches go up to 11.