The Jacuzzi of Despair - EWTS #002

Joe: Hello, and welcome to Enough with the Science. I'm Joe.

Senan: And I am Senan, and this week we're delving into the mysteries below the ocean floor, to discover all about the Jacuzzi of Despair.

Joe: That's basically a summary of my entire life.

Senan: (laughter) The jacuzzi part or the despair part?

Joe: Well, there's a lot of the despair, and there's a lot of water, so.

Senan: So does your, does your desperation bubble up mysteriously?

Joe: Yes, only when you ask me questions like that. I'm usually grand before that.

Senan: (laughter) So we're going to be talking about some of the stuff that's on the floor of the sea. It's not what everybody possibly thinks, it's just a featureless desert down there, but there's a lot more to it than that. There's volcanoes, there's lakes, there's nodules, and of course, my personal favorite, the zombie bacteria.

Joe: And this is all in the pitch dark?

Senan: Oh sure, yeah. I mean, once you go down deeper than, like, I guess, you know, 80, 90 meters, the light doesn't penetrate any deeper than that. But the ocean is a hell of a lot deeper than that. So yeah.

Joe: And is there a point, there's a point where like if you drop a person, or something, into the ocean, there's a point where they will just naturally sink and continue to sink indefinitely.

Senan: I guess what you're talking about there is pressure. So, if you take a lungful of air, and you hold your breath, and you jump into the sea, initially your head might go under the water, but if you just keep holding your breath you'll pop back up again because, you know, your chest is full of air and that's acting like a float keeping you up. But if somebody was to actually then drag you down into the depths, we'll say it's like the concrete boots the mafia use, what's happening is the pressure is increasing as you go down, down, down. And in fact, a lot of the stuff we're going to talk about today is related to pressure, and increasing pressure. Because the deeper you go into the sea, the more the pressure increases, and it increases dramatically. So, if you're standing on the beach, the air pressure that's pressing in on all sides of your body is roughly one kilogram per square centimeter. So that's like, look at the nail on your pinky, that's like for most people roughly one square centimeter. So there's about a kilogram pushing in on that and every other square centimeter in your body.

Joe: So if I wanted to lose weight I'd just have to climb a mountain?

Senan: Well, yeah, you might lose pressure, I'm not sure about losing weight.

Joe: Dammit.

Senan: You would actually use lose a slight little bit of weight because you'd be that little bit further away from the center of gravity of the earth.

Joe: I was right.

Senan: Be hard to measure it. But anyway, for every, so as I said, roughly one kilogram per square centimeter while you're standing on the beach. You hop into the sea, put on your scuba gear and you go down 10 meters, and now you've doubled it. Now it's two kilograms on every square centimeter. And you go down another 10 meters, and it's another kilogram, so that's three kilograms now, and so on. So for every 10 meters further down you go into the ocean, the pressure increases by roughly one kilogram per square centimeter. So when you go to the really deep ocean, you're talking about massive amounts of pressure, and that has all kinds of interesting effects.

Joe: Okay, such as?

Senan: Okay, such as, let's say a ship sinks, and there's a trapped air space, like some kind of a tank or something in the ship that's full of air. And the ship sinks towards the seabed. Eventually, it reaches a point where the pressure that's on the outside of that tank is greater than the strength of the metal the tank is made from, and it just crushes it because the air in the tank is compressible. So, it's like any gas, it can be squashed by pressure. So the air in the tank is not offering any resistance really, or very little resistance, to the pressure of the seawater. So all that's stopping the tank from getting crushed is the actual strength of the metal. So eventually the pressure of the seawater as the ship is sinking towards the bottom just exceeds the strength of the metal and squashes it. So that's an example of the kind of...

Joe: So once like a ship starts sinking towards the bottom, it gets to a certain depth and it just like squishes like a can?

Senan: Well, only the enclosed air spaces in the ship.

Joe: Ah, okay, right.

Senan: So, you know, probably most of the ship, the water can find its way into the inside while it's sinking, and that then doesn't crush the ship. So the metal, the solid metal of the ship, as long as there isn't an enclosed air within it, doesn't really get crushed by the water.

Joe: So it still resembles a ship then on the seabed?

Senan: Yeah, yeah, it does. I mean, when it crashes into the seabed it might actually get buckled or something by the force of the crash, but other than that, yes, it typically resembles a ship when it gets down to the bottom.

Joe: And so what sort of world is it going to experience now when it sinks gently to the bottom of the ocean?

Senan: Well of course there's the zombie bacteria. We have to, we can't let today's discussion finish without mentioning the zombie bacteria. So some of these guys could have been alive for 100 million years. That's the same organism. Not, we're not talking about his parents or his grandparents. Some of these bacteria...

Joe: Isn't that a species? So this is one, this is a single individual?

Senan: Well, I mean, yeah, it's a species, but some members of that species may be alive for... And the reason for that is, so these guys are underneath the sediment in the really deepest parts of the ocean. So down there, there's practically no oxygen dissolved in the water. There's almost no nutrients for them to exist on. It's extreme, there's extreme pressure which just makes it difficult for any living creature to survive, and then it's very cold as well. So take all those things together, it's a real extreme environment, and those creatures have evolved to have an ultra-slow metabolism. So their chemical processes in their body work far, far slower than ours, which allows them to exist without using much energy, and individuals then live for a long time.

Joe: Could this be like some used as an excuse for not being particularly productive in work? That you have just...

Senan: A very slow metabolism.

Joe: A very slow metabolism.

Senan: There's too much pressure. Sorry I can't do me work, there's just too much pressure. And it's awfully cold in here.

Joe: And so they're zombies because they're almost dead, or they're undead?

Senan: But because they're like the living dead, yeah, yeah, yeah. And it's interesting for scientists to study them because, you know, it's theorized that if we find alien life on other planets, it may be in the form of bacteria of some kind. And say the moons of Jupiter or the moons of Saturn, there, some of them are covered in ice, extremely cold, but probably have liquid oceans underneath the ice. And it's possible we may find bacteria like this in those places. So it's useful to study the zombie bacteria.

Joe: And how did these guys decide where to end up? Was just luck?

Senan: Well, life tends to find a niche. Like, anywhere that life can possibly exist, it generally will exist eventually. Something will evolve to fill that gap. So, you know, the bacteria, they probably started out, or their ancestors probably started out their lives as fairly ordinary bacteria living on the surface of the earth. Somehow found their way down to the seabed, maybe in the body of a dead fish or something, you know, who knows.

Joe: Okay.

Senan: So yeah, so that's the zombie bacteria. Now another cool and slightly weird thing is the brine pools, or also known as the upside-down lakes.

Joe: Yeah, I like this idea. Upside-down lake.

Senan: So it's weird to think that down on the seabed there can be a lake that's not the sea. It's like a separate body of water, even, it's like a sea within a sea, if you like. And what we're talking about here is some pockets of water that have become gradually more and more and more salty. And that makes them denser, so the really, really salty water is much denser than ordinary seawater, and it tends to sink underneath the ordinary seawater. It sits on the seabed and it finds depressions in the seabed. So any little bowls or hollows in the seabed, it just naturally flows into them because it's denser, heavier than the normal seawater. And then it just sits there. And you get these almost stagnant, not quite stagnant, but, you know, these ponds that are sitting on the seafloor that don't change very much for thousands of years.

Joe: And these were discovered just by virtue of how salty they were, or?

Senan: Yeah, I think, one aspect of them is very, very few sea creatures can survive in such salty environments. So most, you know, it's like the Hotel California, if you're a fish you can enter but you can never leave because the salt in there will kill you. So if you happen to swim into it, that's it, you're a goner in a few minutes because your body just can't cope with that salt. And that's where we spoke earlier about the Jacuzzi of Despair. That's one particular notable brine pool in the Gulf of Mexico that is particularly salty and practically everything that wanders in there dies.

Joe: And what, like, what kind of size are we talking about? Are we talking about puddles? Are we talking about...

Senan: Oh no, I mean, potentially we could be talking about something the size of a lake that's on land.

Joe: Right.

Senan: You know, I mean it's, if the depression is big enough, the hollow in the seabed is big enough, then eventually more and more of that stuff is going to collect in there.

Joe: And so that's connected to the whole despair thing too, the depression.

Senan: Yeah, it is. But, of course, as I mentioned earlier, life can find a way, and there are extremophile bacteria living in there.

Joe: You just love that word.

Senan: I think I do. And I suppose our zombies from earlier are another example. Extremophile just means bacteria that are able to live in extreme environments that most creatures can't live in. So these guys have evolved super tough cell walls so the salt can't destroy the walls of their cells, and their chemical processes have adapted to high concentrations of salt. And they're able to eke out a living there where nothing else can, nothing else other than tube worms. And the tube worms...

Joe: Tube worms?

Senan: Yeah, tube worms, there's lots of species of tube worms, and they're called that because they construct, literally construct like a tube, like a straw sticking up out of the seabed, and they live inside in that tube. They poke their heads out to get food or whatever, but that's like their refuge, they build their own house.

Joe: So they're kind of like the apex predator of the Jacuzzi of Despair, is the tube worm.

Senan: Well, yeah, there's not a lot of competition really. So they have a kind of a symbiotic relationship with the bacteria I mentioned earlier. So they actually, the bacteria have figured out how to harvest energy from the chemical processes in the salty water, and the tube worms are piggybacking on that and borrowing energy from the bacteria.

Joe: Not really selling this as a holiday destination though.

Senan: Well you just never know. I mean some people want to chill out, and by god you could certainly chill out on the ocean floor.

Joe: So again, because I'm trying to picture these things, but of course this is all in the pitch black, in the minus gazillions of degrees cold.

Senan: Yeah, yeah, yeah.

Joe: And with like ridiculous...

Senan: Pressure.

Joe: ...pressure.

Senan: Yeah, ridiculous amounts of pressure, yeah, yeah, yeah. Yeah, it's like an unimaginable environment. In fact, if you try and compare it with, say, being an astronaut in space wearing a space suit, that environment where there's no air, that's actually a far more benign environment because the astronaut's suit only has to hold in one atmosphere of air. That's roughly one kilo per square centimeter. Whereas if you have an aquanaut, we'll call him, an underwater astronaut who goes down to these extreme depths, his suit might have to withstand hundreds of atmospheres, hundreds of kilograms per cubic centimeter. So it's actually quite a hostile environment.

Joe: You're talking about Tony Stark type Iron Man suit.

Senan: Yeah, that's it. But while we're on the subject of weird things on the seabed, the explosive mud volcanoes are next one on the list.

Joe: I don't know where this podcast just veers into your imagination, the wonderful imagination of Senan.

Senan: I didn't imagine them, they exist.

Joe: Exploding mud volcanoes.

Senan: Exploding mud volcanoes. So I mean there are, we should point out now, this is not the only type of volcano on the seabed. There are like proper lava volcanoes like we're used to here on the surface of the earth down there also, and that's a complete other story, those are some really interesting chemistry going on around them. Anyway, the mud volcanoes though are a different animal altogether. That nothing to do with lava or magma or anything like that. What happens is you've got these layers, really thick layers of silt and sediment that have loads of dead organic material in them. So that is, you know, dead fish, dead seaweed, fish poo, and...

Joe: Shergar?

Senan: Possibly. For those who don't know, don't understand that reference, it was a famous horse that was kidnapped and never turned up. Anyway, the, so these organic materials that are in the silt on the seabed are gradually decomposing, and methane gas is released as that organic material is decomposing. And sometimes if the silt or the sediment is really dense, that methane gas will build up in a pocket, an enormous pocket, underneath tens or hundreds of meters of silt. So you've got this reservoir of methane gas that's gradually building up and building up. And then sometimes the pressure in it increases because it's confined in a tight space, and eventually the pressure of the methane overcomes the strength of the pile of mud that's on top of it, and it literally explodes. So you get this huge outpouring of trapped methane gas like a volcano that splatters mud up into the water column, you know.

Joe: But it's not, it's not on fire, it's just gas throwing mud?

Senan: So although methane is flammable, there's nothing to, it would be very difficult, for starters there's not much oxygen down there so the methane would need oxygen to combust. But even obviously the presence of water would make it very difficult for it to actually go on fire. But it has some very interesting and weird potential ramifications. One is that it could sink ships that are above it.

Joe: Bermuda Triangle? This is Bermuda Triangle territory.

Senan: This could well be the cause of the Bermuda Triangle. Essentially what's happening is that you get this massive sudden release of methane way down several kilometers down below the surface of the sea on the seabed. And as it bubbles up towards the surface, the bubbles get smaller and spread out more and more and more, so you get like this fizz in the water of methane bubbles. And that water, effectively its density is now being lowered by all this gas that's mixed in with it. And the Archimedes principle that allows boats to float on the surface of the sea relies on the water having a certain amount of density. So the less dense the water is, the harder it is to get something to float on top of it.

Joe: Right.

Senan: So potentially if that fizz of methane bubbles comes up around a ship, it could locally reduce the density in that area and allow the ship to actually sink, because the density of the water is temporarily reduced enough to not allow the ship to float. So it's pretty scary stuff. Now, no actual recorded case of it happening, but then again would anybody survive?

Joe: Well, like kind of, I mean all those ships that went missing. How did they explain the planes though? Would it affect the planes in the Bermuda Triangle?

Senan: Uh, I don't think so, I think I don't think it would unless something ignited this huge cloud of methane and just burnt the plane out of the sky, but you know I suppose anything's possible.

Joe: Unfortunately we might return to this in our investigation series.

Senan: But you did, I want to go back to something you mentioned a minute ago and that you said could these methane volcanoes go on fire. Not themselves, but there's a very interesting thing happens with methane at great depth and pressure and low temperature. It combines with the seawater to form something that we call fire ice. So it's a peculiar mashup of frozen seawater and...

Joe: This is now, we're into Game of Thrones territory, fire ice stuff.

Senan: So yeah, it's really one of those really peculiar substances that only forms down at the seabed under the right temperature and pressure. It essentially locks up the methane in this icy slushy substance. And if you retrieve some of that and bring it back to the surface, it's quite unstable, it needs that pressure and temperature to maintain its structure. So when you bring it back up to the surface, the pressure reduces, the water is warmer. When it comes into contact with the oxygen in the air, when you bring it out of the sea, it can suddenly burst into flames.

Joe: Right.

Senan: So you can get this spontaneous combustion just by virtue of the fact that you have brought it into contact with oxygen at lower pressure than where it would normally live.

Joe: This must have been a kind of unpleasant surprise for the first people who brought it up.

Senan: Yeah, yeah, absolutely. And I mean it's something we'll touch on later, there's people trying to figure out how to mine this stuff because methane is a fuel, you know, you can, in fact rockets use it. And if this stuff is just lying around in the seabed, if we could figure out a way of bringing it to the surface without it getting unstable and just evaporating and burning, we might be able to harvest that fuel and make good use of it. Mind you we probably have enough hydrocarbons already being burnt in the planet without more.

Joe: But like, because of the pressure though at the, where it is on the seabed, obviously it's squished into, like, so when you bring it up it will expand, be expanding the whole time you're bringing it to the surface.

Senan: Yeah I'm not sure does it, I know there has been cases of where it has been brought to the surface and it spontaneously bursts into flames. So whether some of it kind of evaporates or dissolves away while you're bringing it to the surface I'm not sure to be honest with you. But I guess it is, sounds based on those occurrences that have happened, it looks like it's possible to get it to the surface in one piece. Mining it may well prove to be possible in the future, but it might not be a good idea from a global warming perspective.

Joe: When has that ever stopped us?

Senan: Yeah indeed. So the next, while we're on the subject of mining, we're going to talk about something with the cool name of manganese nodules.

Joe: Oh, here we go. It sounds like something you have to go and see a specialist for. Quick, we make money.

Senan: So these are effectively sea potatoes. They're little lumps lying around in certain parts of the seabed, about the size of a potato, and composed of mostly manganese metal. They have formed incredibly slowly, and again it's down to the temperature and the pressure at those depths to allow them form. But there is minute trace amounts of manganese dissolved in seawater. So, you know, the seawater at some point in its life cycle has been in contact with rocks which had manganese in them, some of that manganese has dissolved out of the rocks, or maybe volcanoes, underwater volcanoes have carried up manganese that has dissolved into the seawater. So anyway, somewhere along the way the seawater picked up this tiny, tiny, tiny amount of manganese. And the conditions are right at the seabed in certain places for that manganese to gradually harden into these little nodules, but it's an incredibly slow process. So it's estimated that these nodules get bigger by one centimeter every million years.

Joe: It's not really a spectator sport watching this.

Senan: Yeah, if you come back in a million years you might just be able to, if you measured the width of one of these little sea potatoes, it might be a slight little bit bigger than it was a million years ago. But there are in certain places tons and tons and tons of them just lying on the seabed with this valuable precious metal waiting for us to pick them up. So there are companies working on mining that stuff, but of course like anything else that involves mining the seabed there's huge environmental risks because, you know, if you have to tear up huge chunks of the seabed to get a decent quantity of this thing.

Joe: Couldn't you just like put a magnet on a string?

Senan: Yeah, I don't know if manganese is magnetic, I don't know. I know manganese magnet, manganese magnet...

Joe: One would think it would be attracted to magnets.

Senan: That's our homework for our listeners this week is to Google whether manganese is magnetic or not.

Joe: We come up with more questions than answers.

Senan: And what's the use for? What, like I mean what do we use manganese for?

Joe: That is the second part of our listener's homework this week.

Senan: We're going to go through all this trouble to get the manganese up and then realize, actually, we have no use for this. It's inconvenient paper weight.

Joe: But you mentioned earlier on ships sinking.

Senan: Oh yeah.

Joe: That was the methane explosion.

Senan: Yeah, yeah, yeah.

Joe: And loose lips apparently.

Senan: Loose loose lips sink ships, particularly after you've had plenty pints of beer, trying to say that is definitely going to sink whatever ship you're on. Anyway we should probably talk about the deepest known shipwreck.

Joe: Okay.

Senan: And that's a World War II vessel from the United States called the USS Samuel B Roberts. I've no idea who Samuel is before you ask me.

Joe: I wasn't going to ask you. Everybody knows who Samuel B Roberts is.

Senan: Anyway this boat is nearly seven kilometers down. So that is significantly deeper than the famous Titanic wreck for example. Pressure massive down there. So pressure is nearly 700 times the pressure of what we have here on the surface. So if you imagine every square centimeter of that boat is being subjected to about 700 kilograms of weight from the pressure of the water. Needless to say any enclosed air spaces in that boat have long since collapsed. But it is, you know, there are practically, almost no submarines that we have developed capable of going down to those depths because of the pressure. Because remember if humans want to go down in a submarine there's got to be an enclosed air space, that's the air those humans are going to breathe. So the structure of the submarine has got to be strong enough, and of course there's that famous case of a couple of years ago of that private submarine that went down to the Titanic and imploded under the pressure. It was generally any of these really deep vessels are only going to be explored using robots that, you know, don't require, the robots don't require an enclosed air space like we do.

Joe: Okay so it's like a drone essentially.

Senan: Yeah, an underwater drone, but it's still technically challenging to build a robot that will function correctly at that depth and temperature and pressure of course. So yeah, but that's, it is useful, it allows deep shipwrecks like that allow scientists to discover how metals and other materials degrade in a very extreme environment. So you learn new things about metals and how they degrade.

Joe: And would they normally, like with the drones, would they send down like a submarine a certain depth and then fire off the drones? Or do they just send the drones out from the ships?

Senan: Most of them the drones are tethered from a ship. So there's like a long cable going down to the drone. Unlike, obviously flying drones use radio waves typically to be controlled, but it's not really feasible in the sea because radio waves don't travel very well underwater. So usually there's a cable involved. So you imagine you've got your seven kilometer long cable. Imagine driving that. Imagine the storage space you would need on the ship for seven kilometers of cable.

Joe: And just with that particular ship where, where is seven kilometers deep, where is it?

Senan: I'm guessing it's probably in the Pacific because in World War II most of the US activity was in the Pacific but I'm not certain, I honestly could be wrong about that.

Joe: There's a full quiz for listeners this week. A selection of questions.

Senan: We'll be expecting all of those things to be answered by our listeners in the next week or so. Lost continents.

Joe: Ah, very good. Yeah here's the interesting, aha, Atlantis. I knew it. I knew we were going to get to Atlantis.

Senan: Lost continents. So it's a thing. Atlantis probably a myth but lost continents are really a thing. There's a famous one called Zealandia in the Pacific. I mean it was huge, it was half the size of Australia. And essentially something called plate tectonics did it in. So what's plate tectonics? As a lot of people probably know the answer to this but I guess we should probably talk about briefly what it is.

Joe: It's what you do before when you're organizing your wedding and you're trying to decide what type of glass ware and cutlery and plates you want.

Senan: That yeah, science of that. There must be a science of that, people spend months choosing stuff. So it's, the earth really is like an egg. You know there's this very thin shell of solid ground that we live on called the land, and underneath it there's this massive amount of gooey magma that most of the planet is composed from this liquid. And the shell is just floating around on top of the liquid. So the land we live on is a thin crust that's just floating around on top of this molten lava. And it's actually not, unlike an eggshell, you know a chicken's egg or whatever, it's not one complete unbroken shell. It's like several different slabs that are floating around, and we call those plates, we call those the geological or tectonic plates. And there are currents in the magma, in the lava in the center of the earth because of different differences in temperature, some places are hotter than others. There are convection currents that slowly move the plates around. So we're floating on top of this goo and it is moving slowly and pushing us along with it. So in the case of poor old Zealandia, the lost continent, what happened was the plate that it sits on got pulled apart by two different currents that were essentially pulling at different sides of the plate in different directions. So it got stretched. And it got thinner and thinner and thinner and eventually it was so thin that it wasn't high enough to poke above the waves and it sank, sank into the sea.

Joe: Because the land literally got stretched?

Senan: Stretched thin.

Joe: But this just, this didn't happen in 15 minutes obviously, this was...

Senan: No. I'm sure the locals probably had time to evacuate.

Joe: Were there locals even at when this was occurring?

Senan: You have me there. I mean we're talking about a long time ago so the locals probably didn't look like humans.

Joe: Right.

Senan: They probably had horns and scales and...

Joe: The dinosaurs.

Senan: Yeah quite possibly yeah. And there's actually another one as well. So Zealandia is kind of the big famous one that people know about, but...

Joe: And just wait, it sank but it's still at the bottom of the, like it makes up part of the seabed now.

Senan: Yeah, yeah, yeah, yeah. The basically the land just got thinner and thinner and thinner until eventually it fell below the level of the seawater and became the seabed. But there's another one in the Indian Ocean much smaller called Mauritia but again similar process, there plate tectonics stretched the land.

Joe: There must have been like a while just after it happened where you could kind of walk ankle deep for miles.

Senan: Oh a long while. I mean we're talking about all these geological processes happen incredibly slowly. I mean the difference between the land being a meter high and the land being exactly level with the seawater surface of the sea, you could have been talking about a million years just for that much of a change. You know so we're talking about really really slow processes here you know.

Joe: Just go for a stroll, you'd like kind of just have the right size shorts you'd like kind of never get wet just like for a hundred, a thousand kilometers in that direction just up to your ankles.

Senan: Yeah just doesn't come above your knees yeah yeah. So yeah that's lost continents. It's funny all these myths there's a grain of truth in all these myths. Right while we're on the subject of myths let's talk about fairy circles.

Joe: Right. Irish fairies, no?

Senan: Irish fairies, leprechauns probably not. I don't know if the leprechauns were fond of being in the sea. Anyway there are things called sea grass beds. So in shallow enough waters, water is where the sunlight gets down into the seabed, so they were talking about water that's probably 20 meters, 30 meters deep no deeper than that. You've got these vast areas of sea grass. So it's a plant that's a bit like the grass you have in your garden, looks a bit like it, needs sunlight to grow, and tends to cover large areas in shallow seas. But there are bald patches in these beds of sea grass and we don't have an explanation for why these bald patches occur.

Joe: Age?

Senan: Say that again?

Joe: Age?

Senan: Potentially it's receding hair.

Joe: Every bald patch I've ever heard about is age related.

Senan: Yeah. Or it could be just related to the old Jacuzzi of Despair you know.

Joe: Yes, stress.

Senan: Stress, people's hair falls out after too much jacuzzi. But yeah so like there isn't any definite known reason for why these bald patches exist. They're as I say they're sometimes called fairy circles. There's some theories, some people think maybe it's burrowing shellfish that are kind of eating up the roots in certain areas. Others think maybe our friend methane is seeping out of the silt and poisoning the plants in small areas. But my favorite explanation is there alien landing pads for spaceships. Because let's face it say you're aliens and you want to come and observe the earthlings and you don't really want the earthlings to know you're around. Where else would you land your ship but underwater where nobody will see it. So I reckon these are where the aliens have been landing their ships.

Joe: You have too much free time on your hands. We just need to set up a camera to watch them and sooner or later...

Senan: I can just imagine the conversation. Mind the grass Zard! Never mind Blarg, it'll grow back.

Joe: So careful traveling over light years through galaxies to land on earth and observe us surreptitiously and they leave a circle in sea grass. How did you discover the aliens? The little mistake. Just one flaw in their strategy.

Senan: Right let's move rapidly along to glass sponge reefs.

Joe: Is there any alien connection to this at all?

Senan: Who knows? This could have been how aliens taught us about fiber optics because it's a really interesting story. So you got these glass sponge reefs, so these really old microscopic glass tubes that are essentially the skeletons of little creatures. So these creatures were able to harvest dissolved silica from the seawater and then form it into tubes around their bodies. Now I know we were talking about tube worms earlier, they're much bigger creatures like a tube worm could be the size of your finger, whereas these things are tiny tiny little creatures that microscopic little thin glass. And they lived in huge colonies so you get this this massive network of these little glass tubes where these things used to live. And you know glass is a very durable substance as long as you don't break it. And so that should be a tagline for a glass company. Glass so durable until you break it. It's great until it's not. So it was the inspiration for fiber optic technology that we use. Because so if you imagine normally if you shine a torch into the night sky, go outside in your garden in the night and you shine a torch, the light dissipates very quickly so it doesn't travel very far. It might travel you know 10, 20 meters away from you and then suddenly it doesn't, you can't see it anymore, it seems to have faded away. But the interesting thing about these tiny tubes of glass in the glass sponge reefs is the light beams get reflected over and back inside the tubes and it allows the light to travel much further distances than it would otherwise. And that is the basic principle of how fiber optic cables work which we use of course for the internet. If you're particularly lucky you might have fiber optic cables coming into your house for your broadband. But it's like the internal walls of the fiber optic cable allow a beam of light, a laser beam as it happens in the case of computer networks, to bounce over and back inside the reflective walls of the glass tube and travel huge long distances without being degraded.

Joe: Now have you just connected these two things in your own head or is there actually evidence that somebody went and looked at these things and went...

Senan: Yeah they discovered that these things were transmitting light along their length you know much longer than light would normally be transmitted. So yeah no it was it was part of research into them that gave the inspiration for fiber optics.

Joe: Obviously these particular things aren't at a great depth.

Senan: No I mean generally most reefs are not that deep you know most reefs are are kind of shallow enough.

Joe: So that's another weird thing we should talk about is the Milky Sea.

Senan: You just collect weird things.

Joe: Well sure look how could I otherwise be sitting across the table from you were it not for my love of weird things. So there was legends from old time sailors that there was patches of the ocean, like massive patches of the ocean that were glowing a dull milky pale kind of color, only visible at night because it's almost not glowing but still just about this milkiness you could see in the sea at nighttime. And for a long time it was just thought to be a sailor's old wives tale as it were. But then satellite technology photographed the sea for us from space at night and sure enough we could see that there are some patches of the ocean that look have this dull milky glow. And it's almost certainly microorganisms like bacteria or plankton or something that are glowing. But we don't actually know what the mechanism is or why it happens or you know what's actually happening there.

Joe: Drugs? They're on drugs.

Senan: It could be a huge bacteria rave.

Joe: No I mean the sailors.

Senan: Oh the sailors. Well I don't think the satellites were on drugs. But some people might be familiar with the dinoflagellates, the...

Joe: No, nobody is familiar with the dinoflagellates. Dinoflagellates sounds like a Tyrannosaurus with a cilice belt. Like it's...

Senan: What belt?

Joe: That belt you know from The Da Vinci Code. Your man flagellates himself.

Senan: Oh yeah yeah.

Joe: Is it cilice? Maybe it's cilice belt or shillelagh. There you go, dinoflagellates.

Senan: I remember your man walloping himself all right in the movie but I don't recall what the thing was called. These dinoflagellates are a different thing. People might be familiar with the idea of certain plankton blooms at beaches at nighttime, the tops of the waves are sparkling or glowing. That's a different mechanism. That's there they're certain kinds of plankton, fairly common plankton that when you disturb them, you know agitate them, splash them around, they for a brief period produce a little sparkle or flash of light. It's a kind of a defense mechanism we think. But that's a different thing altogether.

Joe: It's not a very good one. Like humans immediately like kind of let's do this, look at this, look what I can do.

Senan: Yeah yeah I suppose they probably...

Joe: Didn't realize it was so beautiful.

Senan: Yeah I think it's probably fish and crabs and things that are afraid of the flash of light. But it's cool, I've actually seen it myself once where there was a really particularly strong bloom of these bacteria and you went down to the beach at nighttime and you could literally see the tops of the waves where the waves were breaking were like glowing really, it was amazing. And then if you if you kind of stomped your path up the beach, up the wet beach and looked behind you, you could literally see this glowing trail of footprints behind you coming up the beach. It was amazing. I've only seen it once but it's pretty cool.

Joe: Drugs again.

Senan: Could have done with some that night. Water is a weapon.

Joe: Water is a weapon?

Senan: Water is a weapon and we're not talking about drowning here. We're talking about a...

Joe: Water cannon?

Senan: Water cannon? Yeah yeah.

Joe: That's true actually. I didn't think of that. Water bombs in school.

Senan: Yeah that's yeah. Okay water is more than one kind of weapon then. I take your point there. Anyway I'm using that as a segue into talk about a little thing called a pistol shrimp. So cool little name pistol shrimp. And this little fella, small little crustacean makes the loudest known sound in nature. And it's a byproduct of what he does to stun his prey. So what he does is he snaps his claws incredibly quickly. So the actual movement of his claw is one of the fastest, it's very short, it's only a couple of millimeters, but it's one of the fastest accelerations in the natural world. And what happens is that sudden jet of water created by his claw being snapped causes what's known as a cavitation bubble. And that bubble only exists for an instant before it collapses, and when it collapses it causes a huge noise and a sudden burst of heat in that tiny area where the bubble was, up to 4000 degrees which is hotter than the surface of the sun. It's really incredible that this tiny creature can release so much energy just by snapping his claws.

Joe: I just don't, you know there's only like I just have trouble believing this because why hasn't someone turned this into a superhero?

Senan: Yeah yeah I mean...

Joe: I just don't understand why I haven't seen this Marvel Universe quick pistol shrimp guy.

Senan: You should patent that idea. You'll make millions when pistol shrimp man bursts onto our movie screens. But yeah so we should probably talk about what is cavitation. As I said when the shrimp kind of suddenly claps his claw or snaps his claws, this cavitation thing causes a bubble to appear. So what happens is if you get a very sudden local surge of water, what will happen is the pressure just around where that surge in the water is will drop for a moment. And if the surge of water has been strong enough, you know the acceleration of the little squirt of water has been strong enough, the water, that drop of pressure allows the water to vaporize. And so you get a little bubble made from water vapor. And it only lasts for a second before you get this hot and violent collapse of the bubble again. And that's, it's the collapse of the bubble which actually causes this incredibly loud sound, this little burst of heat and a flash of light. And it's actually boat engineers, marine engineers have got to be careful about how they design propellers because boat propellers can inadvertently cause cavitation. And you get, when the bubbles, the cavitation water vapor bubbles collapse around the propeller, the shockwave that they cause actually eats little holes into the propeller. So sometimes you look closely at the propeller of boats you see all these tiny little holes in it and it's caused by cavitation if the propeller isn't designed properly.

Joe: And does, so cavitation causes the temperature as well? The collapse of it?

Senan: So it's when the cavitation bubble collapses. It's the sudden compression of that water vapor. So any gas that you compress heats up when you compress it. But this compresses so quickly, the bubble collapses so quickly that the compression of that little fragment of water vapor is so sudden that it heats up massively.

Joe: Very good.

Senan: Yeah it's hard to believe though that that can happen underwater and can be caused by a tiny little creature.

Joe: But I mean like 4000 degrees, I mean that would hurt you if it decided to do it near you.

Senan: Yeah but the thing is you're talking about a very tiny area. So you could be talking about a bubble smaller than a pinhead or the size of a pinhead. So the 4000 degrees is in a very localized area and you've gotta remember there's cold water all around it so the heat is going to dissipate very quickly into all that cold water.

Joe: But like if you had like if you were say a Bond villain and you had like a million pistol shrimp in a tank and then some guy number two that like let you down and you press the button and into the tank of pistol shrimp...

Senan: And you could coordinate them all to snap at exactly the same instant...

Joe: Like it's...

Senan: I'm sure you could boil the water yeah.

Joe: Yeah there we go. Another idea I've given away for free.

Senan: Mind you the pistol shrimp might boil themselves while they're at it.

Joe: Well they probably wouldn't mind.

Senan: So you know free meal after you've dispensed with...

Joe: Actually that reminds me, why don't pistol shrimp give money to charity?

Senan: I can't wait, I'm on the edge of my seat here, tell me.

Joe: Because they're so shellfish.

Senan: Ah yes yes I've been waiting all day.

Joe: All day for that one.

Senan: I just can't go on I'm sorry folks we're going to end the podcast here because I just I just can't.

Joe: You can't continue. Not just this podcast, every podcast we're finished now.

Senan: But did you know there's gold in that there water?

Joe: Okay. Well yes you would imagine that it's there's some soluble bits isn't there?

Senan: Um yeah so I'm impressed that you're listening.

Joe: I'm listening to what you're saying I know you don't look it.

Senan: So I don't actually need to explain this we move on to the next topic. So yeah there is, we were talking about manganese nodules earlier and about how they form from manganese dissolved in seawater but there's other useful metals also again tiny tiny amounts dissolved in seawater. So there's gold, uranium, lithium, all of those things would be useful to us. And there is some scientific research going on about could we extract that stuff out of the water. But you're talking about processing an ocean of water to get a few grams of metal. So you know it's a real technical challenge to make it economically viable. And then of course like a lot of these things what are the environmental risks if you do decide to start processing you know mind boggling amounts of water. And how much energy do you have to expend to process that water? I mean it could be far far cheaper to mine the stuff out of the earth than to collect it from seawater.

Joe: Which we shouldn't be doing anyway.

Senan: Well yeah I mean I suppose lithium we all want our batteries in our laptops and phones and electric cars so lithium is useful for that so that's probably one reasonably good use.

Joe: Is that what they give people who are depressed or to calm them down or something?

Senan: Oh yeah I think there is there is a lithium based medicine yeah yeah.

Joe: But we should stop using that.

Senan: It's also a major component in batteries and rechargeable batteries.

Joe: What has the opposite effect on people as it does in batteries.

Senan: So the lithium brings down people's energy level but brings up the battery's energy level yeah it's an interesting dichotomy that.

Joe: Right what else can we get out of the water?

Senan: Well the water itself of course could give us its constituents because water is just made from hydrogen and oxygen, it's a compound of hydrogen and oxygen. And hydrogen burns. And hydrogen is a particularly environmentally friendly fuel because when you burn it the exhaust is water vapor. There's no smoke, no carbon dioxide, no soot, none of that. If you burn pure hydrogen the only thing you're going to produce is water vapor. And so you know maybe we should be splitting, what's it's called splitting when you separate the hydrogen and the oxygen to release those two gases from water. Maybe we should be doing that to generate this environmentally friendly fuel. Problem is of course it takes energy to do it. So you know there are some experimental attempts with fancy membranes that would allow the hydrogen or the oxygen to pass through and separate that way which would not involve expending a lot of energy but I don't think anybody has actually succeeded in getting them to work for you know more than a few minutes before the membrane gets clogged up with something. So the other the other classic way of doing it is splitting it with electricity. So if you literally run an electric current through water the hydrogen and oxygen will bubble off at that point at the point where the electrodes are. But you're talking about using a huge amount of electricity just to get that out. So there's probably no net benefit although some people see it as instead of calling it producing fuel it's an energy storage mechanism. So let's say you have a huge amount of solar panels that are generating far more electricity than you need. You could theoretically use the excess electricity to split water and harvest the hydrogen and at some point in the future use that hydrogen to generate energy or power a fuel engine or something.

Joe: And how like how easy is it to store hydrogen like is it particularly volatile?

Senan: Yeah hydrogen is a tricky one to store because the hydrogen molecule is small. So it's able to leak out through the tiniest crack in a metal or you know the tiniest imperfection in the welding at the corners of a tank or whatever. So hydrogen tanks typically have to be built very robust. And in fact just to touch on one of my favorite subjects for a moment, rockets, the route to the aliens. So NASA's Artemis rocket is partially fueled by hydrogen and they have had a huge amount of technical problems trying with leaks, hydrogen leaks because it is a difficult fuel to contain. So there is there is that yeah. Now Toyota kind of while the whole world was pursuing electric cars Toyota for a while went off and pursued hydrogen. And they produced a couple of experimental hydrogen cars thinking that maybe the hydrogen economy as it's called might actually become a viable thing but it doesn't look like the horse that Toyota backed is going to come in.

Joe: Hasn't they haven't figured out how to harvest the hydrogen yet?

Senan: Well the I think the availability of high efficiency batteries, rechargeable batteries that we have now has meant that electric cars are viable and people have gone down that route instead of the hydrogen route. And they don't have the problems we discussed a moment ago with trying to contain the hydrogen in robust tanks.

Joe: Poor Toyota.

Senan: Well Toyota are the richest car company in the world so I'd say they can cope with it.

Senan: Right let's talk about what the ocean can store for us rather than what can we get out of the ocean, what can we put into the ocean.

Joe: Nuclear waste.

Senan: Well yeah we've done that and it's probably not a great idea. There's a very deep canyon between Scotland and Northern Ireland and there are some nuclear waste dumped in the bottom of that thing and I don't think anybody thinks it's a good idea now. And there's other places I'm sure that are similar. But no I'm talking about what useful things can we store in the ocean. And it's carbon really that we're talking about. Because as we know carbon dioxide is the big culprit when it comes to global warming and climate change and all that. Carbon dioxide that's in the air dissolves into seawater. So the air obviously is in contact with the surface of the sea and a certain amount of carbon dioxide that's from the air dissolves into the seawater and forms a solution of what's called carbonic acid. So that gets stored in the sea, that's a certain amount of carbon dioxide that gets stored in the sea. But then there's also a different mechanism called marine snow. So you know the bodies of animals and plants are substantially built from carbon and when those animals or plants die or start to decompose if they're in the sea fragments of them start drifting down towards the seabed. And you know so you're talking about partially decomposed animal and plant remains, you're also talking about fish poo.

Joe: Great having my dinner.

Senan: All that stuff kind of gradually sinks down towards the seabed and it's known as marine snow and it tends to build up on the seabed and get stuck in the sediment. Now as we mentioned earlier methane it slowly decomposes into methane and some of that methane does get released back into the atmosphere and methane is actually a worse greenhouse gas than carbon dioxide.

Joe: And sinks ships.

Senan: And theoretically sinks theoretical ships in theoretical Bermuda triangles. So it's yeah it's a double edged sword that one. And the other problem with obviously there's more carbon dioxide in the atmosphere now and the combination of the fact that there's more of it in the air and the fact that seawater is getting warmer means that more of it is dissolving into the sea. And that although might sound like it's a good thing is actually making the seawater more acidic. And there are some of the creatures that live in the sea they have evolved to live in a less acidic environment. So that more acidic ocean now is starting to have bad effects on them.

Joe: Is that the one that about the corals the corals are being bleached is that sort of?

Senan: Is that yeah I think that's one component and then some shellfish the calcium shells that they build for themselves are not resistant to acidic water and the shells are getting thinner and less substantial. So there are there are downsides to more carbon dioxide dissolving into the sea. And today we're going to finish up with the wonderful subject of jelly. Jelly here jelly there jelly everywhere. So the fact is we are slowly turning the ocean into a paradise for jellyfish. What we're doing to the ocean they love.

Joe: Do they like the additional carbon? Do they?

Senan: Um well I don't know about the carbon but they certainly like the fact that the sea is warmer. So the warmer seas tend to have lower oxygen concentration in them and that tends to suit jellyfish other than more than other creatures. A lot of their predators we have fished them out so you know we have certain species that eat jellyfish we have fished out those species and their numbers are far lower so there's much less predation of jellyfish going on. And then our farmers understandably like to use fertilizer to maximize their crop yield. That fertilizer gets washed into rivers and eventually finds its way into into the sea and the plankton which are minuscule plants that jellyfish lot of jellyfish species eat love that fertilizer because they're plants you know why wouldn't they love it. So you get these big plankton blooms being encouraged by fertilizer and that also encourages blooms of jellyfish. So there are massive blooms of jellyfish happening now that didn't happen before. And even here in Ireland we had it on the south coast for a few days last year we had what they call mauve stingers we had millions of them and luckily they didn't stay around very long but another side effect of of these greater numbers of jellyfish is that they sting juvenile fish. Some of them do some species sting small little juvenile fish. And so you could get an entire generation of juvenile fish being wiped out by a big bloom of jellyfish. So it's funny as it might sound it's not funny at all you know.

Joe: Yeah it's not just about getting a jellyfish sting while you're on holidays it's slightly more...

Senan: Yeah that could be just everywhere and you know they could reduce the diversity of other species in the sea because they're going to outcompete them you know.

Joe: Just like kind of fire ice cream at them.

Senan: Yeah or the methane fire ice we could fire that at them. So that's that's kind of all we have today Joe unless there's anything...

Joe: I think that was quite a lot. I think you very lucky listeners to this podcast today there was a lot of information there.

Senan: Yeah so uh I don't know have we have we any parting shots to leave with our listeners?

Joe: I decided zombie bacteria was like prime for a limerick.

Senan: Right.

Joe: So um we'll leave you with this poetic license in its. So to qualify as zombie bacteria you must satisfy some strict criteria. You metabolize slow keep the temperature low and avoid causing human hysteria. There you go.

Senan: You're wasted on this podcast.

Joe: No but I will be in about five minutes. Thanks for listening this week.

Senan: Yes that is enough with the science and that is more than enough science this week I think. And yeah thanks thanks for listening and don't forget your homework and we'll see you next week. It's goodbye from me Senan.

Joe: Goodbye from Joe. Take it easy.