A trip to the seaside
This week why whales get dandruff, what seabirds think of wind farms, the plight of coral reefs, we take a look at some giant sea spiders and look at water that can stay liquid below freezing temperature. Plus, we use science to perfect the recipe for a superior sandcastle...
In this episode
01:17 - Supercooling sea spiders
Supercooling sea spiders
with Lloyd Peck, British Antarctic Survey
Lloyd Peck of the British Antarctic Survey explains how some creatures in the Antarctic, like sea spiders, grow to giant sizes!
Chris - Lloyd, so, you work in Antarctica. It's not very Antarctic in here today. In fact, it's approaching 9 million degrees because we've had to turn the aircon off, but tell us about your work!
Lloyd - I've got a group that works in the Antarctic and some of those people there now, at Rothera station currently, it's over 30 degrees here and where there now, it's between about minus 15 and minus 20. So, there's almost a 50-degree difference between where I do most of my work at the moment and the temperature we have here. I'm really interested in how animals not only survive in low temperatures, but actually thrive in those environments and why they are different and how different they are, and I have some examples of that.
Chris - When you say you've got some examples of these animals, what have you got with you there?
Lloyd - Well, some of the animals and some of the adaptations that we have in the Antarctic are very unusual. So, one of the best examples I guess is, there's a group of animals that live around the coast of the UK and you've all been on holiday to the seashore. You've all looked in rock pools and there are animals in those rock pools called sea spiders. One of the biggest sea spiders in the UK is that animal there.
Chris - Hang on. That's your...
Lloyd - That's on the end of my finger.
Chris - ...index finger.
Lloyd - Yes.
Chris - And there's a tiny speck that you stuck on the end of your finger.
Lloyd - It's sitting on the end of my finger. It's about 5 mm across and okay, its legs are curled up so that when it's up and walking around, it's maybe as much as a centimetre across. And if you've looked in rock pools around the country, you will all have seen this animal.
Chris - So, what does it actually look like if we sort of put a magnifying glass on there? What do we see?
Lloyd - They look like an 8-legged spider. They look a little bit more chunky than most spiders. Their legs are a little bit thicker. Their bodies are a little bit more chunky than that but they do look a lot like a spider.
Chris - Are they really spiders?
Lloyd - No, they're not spiders. They're a related group to spiders. Say, there's a big group of animals generally called - the scientific name for them is chelicerates. But in that group, you've got scorpions, terrestrial spiders, and sea spiders. They're called chelicerates because these organs hanging down under their bodies that are hooked that are called cheli. Our sea spiders use those chelis to carry their eggs around while they're developing their eggs.
Chris - But, they don't make webs in the sea.
Lloyd - They don't make webs in the sea, no. There are some terrestrial spiders that live in the sea. They live subtidally and they pull air down from the surface and make little bubbles on the seabed and live in those with their webs. But these are sea spiders. They don't do that.
Chris - But that's not - if I'm honest - and don't take this the wrong way, that's not very impressive as a specimen.
Lloyd - That's one of the biggest European sea spiders.
Chris - Well, that's what I mean. It's not very impressive.
Lloyd - Okay, now we have sea spiders in the Antarctic.
Chris - Okay. [laughter]
Lloyd - Now, this sea spider is about 20 cm from leg tip to leg tip and it's not one of the biggest sea spiders from Antarctica. The biggest sea spiders in Antarctica grow up to 50 cm from leg tip to leg tip.
Chris - I mean, to be fair, that's the size of a dinner plate. That's big.
Lloyd - My dinner plate's are bigger than this, but it is the fair size.
Chris - Big eater...
Lloyd - Okay, it's a big animal, yeah.
Chris - Certainly, it is.
Lloyd - The biggest sea spiders in Antarctica are 3,000 times heavier than the biggest sea spiders in Europe, around the UK, in North America, in all the temporal latitudes.
Chris - What does that eat?
Lloyd - This species eats limpets. They chase limpets around the seabed. They catch limpets and they eat limpets. They have a proboscis that they push under the side of the shell and they eat the limpet from underneath. But sea spiders eat lots of different things depending on the species.
And the reason they get big is because it's cold. The cold allows them to get a lot bigger for two reasons. One is that you need to spend energy to keep your body alive. The bigger your body, the more energy it costs. But when it's cold and you're a cold blooded animal, your metabolic rate is very low because the low temperature pushes your metabolic rate down. So, the cost for each piece of tissue is a lot less. The metabolic rates of these animals are 30 times lower than similar animals in the tropics.
Chris - Does it also help them Lloyd, the fact that because it's really cold, there's so much oxygen in the water because when the temperature of water is lower, you can dissolve more gas in it when it's hot, can't you?
Lloyd - There's roughly twice as much oxygen in a litre of seawater in the Antarctic as the tropics. So, there's more oxygen available to fuel your metabolism. The metabolic rate is lower, the costs are lower, the two trade-off together to make much bigger animals in some groups. We have a group of animals that were related to wood lice, isopods that grow up to about 14 or 15 cm long. It's another group where we see giant size. So, gigantism is one thing that happens at low temperature. It also means because their metabolic rates are low, that if things go bad, they can just sit and wait. We've done experiments with some predatory snails offering all the food types they like and some of them have eaten nothing for 3 years - and they're still walking around the tank, they're still reproducing, they're still interacting with each other. The average number of males was one male every 11 months. So, if things go bad, you can just wait for them to get better.
Chris - I mean, that's nearly as bad as a Cambridge University student.
Lloyd - Well, the alcohol is not available for our animals in the aquarium, but the food is limited, yeah.
Chris - Are there any other animals that are also huge like that or are these the exception? Is this sort of the rule down Antarctic?
Lloyd - Sea spiders are one of the best examples that we have and there are no lobsters and that type of animal in the Antarctic to be predators. So, sea spiders have radiated out and there are lots more sea spider species in the Antarctic and elsewhere. We have 10 legged groups and 12 legged groups that you don't have anywhere else. But there are other groups. We have ctenophores, sea gooseberries that look like gooseberries in most oceans of the world. They get up to about 80 cm long in the Antarctic and are much, much bigger than a rugby ball. So, there are lots of groups that do get bigger, but not everything does get bigger. There's got to be an ecological reason why large size is an advantage before they do get to that large size.
Chris - But there've been some reports off the coast of Cornwall recently of these barrel jellyfish that are a meter across. So, you don't just have to live in really cold water to get big though, do you?
Lloyd - The biggest jellyfish in the Antarctic are even bigger than that. I've seen one, 140 feet long and 2 meters across in the bell. But the size is relative to the architecture of the animal, but also then temperature has an effect on how big that architecture can be.
Chris - Do they sting?
Lloyd - Yes, they do.
Chris - Painful?
Lloyd - Well, when I'm diving in the Antarctic, it's cold and I wear a full dry suit, so it doesn't matter how much it stings. It doesn't get through the dry suit and I've never handled one with gloves off, so maybe. I don't know.
Chris - I think you should try, Lloyd. Any questions for Lloyd so far?
Bob - Hi. I'm Bob from Godmanchester. Thinking about temperature and keeping warm enough, how does being in the sea compare to being up on land in the Antarctic because up on land, you've got the wind, but under the water, you've got the water around you rather than air which is better at sucking the heat out of you?
Lloyd - You're absolutely right. There are very different adaptations on land and in the sea. If you're a warm blooded animal then heat loss is a big problem at low temperatures. Most animals, most of the warm blooded animals, the seals for instance use fat as an insulator. The fattest animals on the planet are in the Antarctic. The elephant seals are maybe 45% fat and the biggest elephant seals are 3 tons. So, that's 3 times the biggest shire horse you've ever seen. And they keep warm by having lots of fat. If you're cold blooded then you're the same temperature as the environment. In the sea and on the land, that's a very different problem because the land gets down to certainly minus 20, minus 30 and you have to be able to survive those low temperatures that you don't have in the sea. You'll also have dehydration as a problem.
Chris - We're talking about really cold stuff. You've got in your experiment.
Lloyd - Yeah, so animals on the land, really good question, have lots of ways of surviving really cold temperatures. One is to use anti-freeze, but we have an example of another mechanism here and what I want is somebody from the audience to come out and stand close to where we are now. Can we have a volunteer? Come on.
Ginny - Yeah, got someone over here. What's your name?
Jessica - Jessica.
Ginny - Jessica, okay brilliant. If you come and stand with me here. So, I can see a big machine there that's making quite a lot of noise. What have you got going on here?
Lloyd - Well, what we've got is, we've got a chiller, a cooling unit. In that cooling unit, I've got some beakers with a liquid in. Here's a colourless liquid and what I want you to do is tell me what that temperature says on our thermometer that's in one of our beakers. There's a minus...
Jessica - 27.
Lloyd - Oh no, 2.7. There's a dot. So, the temperature in this beaker is minus 2.7.
Ginny - So, what does that look like? What can you see in there?
Jessica - It looks like water.
Ginny - Is it water?
Lloyd - So, what happens to water when you take it down to minus 2.7?
Jessica - It turns into ice.
Lloyd - Is this ice?
Jessica - No.
Ginny - He's just drunk it.
Lloyd - Do you want some, Ginny?
Ginny - Go on then. I'm not sure I believe that it's water because if it's minus 2.7, that's definitely still a liquid. That shouldn't be happening.
Lloyd - It should be ice, shouldn't it, but it's not. You could try some and drink some and tell me what you think.
Ginny - Okay, it's definitely water. It's not vodka. I thought you might be tricking me.
Lloyd - No, okay and it's minus 2.7. So, if I drop a piece of ice inside, you can start to see that ice grows in the water around the piece of ice. Can you see that?
Jessica - Yeah.
Ginny - So, what can you see around the ice?
Jessica - Spikes.
Ginny - It looks like little spikes are coming out from the ice and the piece is getting bigger, isn't it?
Jessica - Mm-hmm.
Ginny - You dropped in a tiny weeny piece of ice and now, the ice is almost kind of half-filling the beaker. What's happening?
Lloyd - You can see ice growing before your very eyes in the water. Shall we do that again? Here's another one, minus 2.7. Do you want to tell people how fast the ice grows when I drop this little piece of ice inside? Here we go.
Jessica - Very fast.
Lloyd - So the question is, what's going on? The answer is, this is called supercooling. If you take water out of your taps and put it into your freezer, it freezes at 0 degrees. The reason it freezes at 0 degrees is, there are lots of impurities in the water that ice crystal starts to grow on.
If you take all of those impurities out then there's nothing for the ice to grow on and the ice won't grow as quickly. You can get the purest water we can get. You can get down to about minus 40 before it freezes.
This is water from my lab. For this, technically it's called 18-mega ohm per cm water. You measure purity of water by its resistance to electricity as it gets purer and purer, and this is really pure water. I can get this down to about minus 6 before it freezes. So, this is supercooling and some animals use supercooling to avoid freezing in the Antarctic in the winter. They get rid of all the ice nucleators, all the particles that ice can grow on. They throw them out of their body and that drops their freezing point by maybe as much as 5 or 6 degrees and you add anti-freeze to it and they can then go down below minus 20, maybe down to minus 30 before their bodies freeze. Thank you very much for coming up.
Ginny - So, what kind of animals use this?
Lloyd - The best known animals are very small insects, microarthropods - things called springtails and mites and they're the real Antarctic terrestrial animals, the biggest Antarctic terrestrial animal that lives there year-round, is about 2 mm long and it's a mite or a springtail and they use supercooling and anti-freeze to survive down to about minus 35 degrees and they can survive in the crevices during the Antarctic winter, protected a little bit by snow from the minus 50s and 60s above.
Kelvin - I'm Kelvin from San Francisco.
Chris - Gosh! You've come a long way.
Kelvin - I have and since my name is Kelvin, I think it's very appropriate that I ask this question. Is there any way for us to do this at home, so for example, by distilling water?
Lloyd - If you can get your hands on any really pure water, yes, you can. Your problem is going to be getting it low enough so that it's below freezing and getting it at exactly the right point. The equipment I brought in here will run at minus 3 degrees all day which means I can set it up and running. If you put it in your freezer, it's going to go - because your freezer is going to be at minus 18, your timings gonna to have to be good. But I've done this at home in the freezer and I bought ultrapure water from the chemist and it works.
Chris - Excellent! Any more questions?
Kate - My name Kate Bacher. I'm also from Godmanchester. You were talking about anti-freeze. Is that anti-freeze as we would know it that we put in our cars?
Lloyd - It's not the same as you would put in your cars, but there are lots and lots of chemicals that are used by animals as anti-freezes. There's a whole range that are used by fish in the ocean that are proteins and glycoproteins. Insects have a barrage of anti-freezes, glycerol they can use and they have a whole range that will allow them to survive very, very low temperatures. They don't use glycol. Ethylene glycol isn't one that they commonly use, but they got somewhere between 50 and 80 different anti-freeze molecules. There are a couple of moths that can turn their bodies into 60 or 70% glycerol for the winter time to survive in a kind of semihibernation state over a long period of time and then when the temperatures come back up, they can resynthesize it back into the functioning molecules that they need.
Chris - Georgia, you've got something.
Georgia - Mark Shiverett on Twitter wants to know, "Are there any antibiotics or other natural products which come from the sea?"
Lloyd - There are lots and lots of natural products that come from the sea. So, there are alginates that are used in ice creams and there are many products, but I don't know about antibiotics. I suspect there are because I suspect that some of the animals that we have in the sea and some of the bacteria that we have in the sea all interact and lots of them have chemical defences. Some of those chemical defences will have antibiotic properties.
Georgia - So, what are these products which go into ice cream?
Lloyd - Well, alginates for instance...
Chris - I see which way Georgia' mind works.
Lloyd - Yeah, there are several low temperature products that are used to keep things slightly plastic in their makeup and they're used to help control the size of crystals when ice grows. And so, if you control the crystal size very carefully, you can make a smoother ice cream. And so, those products are used for those sorts of things with ice creams.
Chris - Ladies and gentlemen, Lloyd Peck from the British Antarctic Survey...
16:02 - Are wind farms affecting seabirds?
Are wind farms affecting seabirds?
with Viola Ross-Smith, British Trust for Ornithology
How are British sea birds reacting to offshore wind farms? Viola Ross-Smith from the British Trust for Ornithology is aiming to find out just that, but first she showed us a few of the seabird species from around Britain...
Viola - So, I brought some props with me. I haven't got a sea spider, but I have got a box of seabirds behind me if anyone wants to look at them.
Chris - You've got a what?
Viola - A box of seabirds.
Chris - Alive?
Viola - They're dead.
Chris - You're not doing your job very well then if they're dead.
Viola - They've been dead for about 90 years. If people are interested, I can get them out. Do you want to see? Okay, so these are skins so they look a bit odd. Let's start with a chick. This is a little fluffy lesser black-backed gull chick. It was probably about a day old when it died 90 years ago, but this is a species I normally work on actually, lesser black-backed gull. I put these tags on which I'll tell you about later. Just to show you the kind of range we get in the UK, this is a little tern. So these breed on the coast of Suffolk and Norfolk not too far away. This species got quite a long - it's in breeding plumage. It's got a long yellow beak, a black hood and then typical for seabirds, it's got a pale grey back and a white plumage underneath. Working up the terns, this is a common tern. So, it's about twice the size of a little tern.
Chris - Have you got U-turn in there?
Viola - I don't have a U-turn but I've got a sandwich tern which is the biggest tern you normally get in the UK. This breeds mostly in North Wales Anglesey in the UK and it would have a black hood, but this specimen is going out of summer plumage into winter plumage, so the hood has sort of receded back. It's just patchy black.
Ginny - Are you saying that they change colour with the seasons?
Viola - Yeah, they do. So, most seabirds in the winter like puffins for example - of which I have one here...
Chris - Here's one I made earlier.
Viola - Well, some were made several years ago. In the winter, they don't have these characteristic clown-like colours around the beaks. In fact, some of the bits on their beak just fall off. So, when they're out to sea in the winter, they just look sort of dark and just not very interesting. When they come in to breeding plumage, they develop all exotic colours around their bill in terns and gulls, if they have a hood, they grow it in the summer normally. So yeah, carrying on with my little exploration of British seabirds, I've got a few auks. This is a little auk. They're kind of compared to the terns the terns are long and thin, and streamlined. These ones are more sort of bottle-shaped almost. They look more like bullets or something. That's because they're pursuit divers. So, they're not very good at flying, but they'll dive straight into sea and then they swim quite strongly. They chase after sand eels and other small fish.
Ginny - Looks a bit like a tiny penguin when you see penguins underwater and they look quite streamlined and elegant.
Viola - Yes, so interesting examples of convergent evolution. So, the auks are northern hemisphere penguins really in many ways. Unlike the penguins, the ones that are still extant, do fly. There was the great auk that is now extinct which didn't fly, which is much bigger than these guys. But yeah, in many ways, they are northern hemisphere penguins. So, we've got a little auk, we've got puffin which is also an auk. I don't know if I need to describe puffins. I think everybody on the radio knows what they look like. Although I think people are often surprised by how small they are.
Ginny - Yeah, I was quite surprised, but the beak is very distinctive, that big kind of triangular, colourful beak.
Viola - Yeah and this is quite a poor specimen in terms of the colours. So, when you see them on a breeding colony, I would recommend going and see puffins in breeding colonies if you never have. They're really quite spectacular.
Ginny - Is there more in there? It's like a Mary Poppins box.
Viola - I've only got a couple more if people can bare it. So, I've got two more auks here, guillemot and razorbill. They're quite similar large auks, but the razorbill has got a much curved, thicker beak than the guillemot. The guillemot has got a narrow, black, pointy beak. The razorbill has got this black beak with characteristic white stripes on it.
Ginny - Is that because they eat different things?
Viola - Yeah, it' quite interesting actually. They've got very similar niches, but they dive to slightly different depths. They co-exist, they nest on the same ledges and seabird colonies, but they have to differentiate slightly. Otherwise, they wouldn't manage.
Finally, I thought I'd go for the bigger seabirds in the UK. So, this is a first winter grey black-backed gull. It doesn't normally look like a spear. It's because it's a skin and it's not stuffed very well. But this is our largest seagull. Well, in the world actually, not just in the UK. If I could unfurl its wings, it would have a 2-meter wing span.
Chris - Do they live all around the UK?
Viola - Yes, they do. In the winter, they tend to migrate off more out to sea, but they stay around the UK all the year round unlike some of the other gulls I work on. Someone once described them as the lions of the sea to me and I think that's quite apt.
Chris - So, if your sort of work is going well, then you should be able to have all of these in fine fettle all around the British coastline. I mean, you're looking at how to conserve these birds and how they live.
Viola - Yeah, we are indeed. So, a lot of the work I do is applied ecology for the BTO. We're funded often by the government to do impartial research. we don't campaign unlike the RSPB. The government wants to know things like, what might offshore wind turbines do to the seabirds. Will they be able to fly around them? Will they fly through them and get chopped up? Will it take away fish that they rely on or will it attract fish and actually help seabirds? So, one of the ways we do this and we've done it on the bird I'm holding right now actually - the great skewer - is we put these GPS tags on them. So, I've got a couple of tags here. They're not cheap. They cost a thousand pounds each. They're very hi-tech, solar powered tags which means that they're long lived. The one I'm holding now is about 5 cm by 2 cm. It weighs approximately 19 grams which is nothing for a massive seabird like a great black-backed gull or a great skewer. I couldn't put it on the little auk or the little tern. They measure 3D position and they give information like acceleration. We can take pictures up to every 3 seconds on them and that means that you can pretty much see what the birds are doing - whether they're flapping, soaring, diving, gliding. You can calculate through the acceleration whether they're traveling on thermals, whether doing dynamic soaring if it's something like an albatross. We've had some of these tags on less black-backed gulls in Suffolk for 4 years now. So, we've got really good information about what they're doing all year round.
Chris - They look like they've got little antennas sticking up off the back. Is that how it gets the data?
Viola - Yeah, well it was how it got the data, but actually, that model, it's been passed around. It's about 4 years old and since then they put the antennas inside and that's because - well, it's less invasive for the bird, it doesn't interfere with their aerodynamics. And also, a bird like a great skewer or a great black-backed gull will just try and turn the antenna off.
Chris - Because it looks like a little bird backpack. How do you put them on? Do you strap them on or something?
Viola - Yes, we've got harnesses made of Teflon which is strapped under the wings and it loops through the little eye holes on the tag. And it just holds in nicely in place for years and years. The birds don't seem bothered. They behave normally. They carry on breeding. They migrate in the case of our lessers. So yeah, it's really interesting and we can see them weaving in and out of the wind turbines. We can see some birds traveling down to Morocco every winter.
Chris - Do you ever see them accidentally not weave around the wind turbine?
Viola - Not yet. If we did, I don't think DEC - Department of Energy and Climate Change who funds the work, I don't think they'd be very pleased some birds are.
Chris - So seriously, what influence of the wind turbines are you seeing?
Viola - I shouldn't pre-empt this too much, but very little actually on our lesser black-backed gulls. They seem to be coping with them absolutely fine. But that's not to say that other seabirds or other non-seabirds can cope with them. I know people think that birds like gannets -they're always looking down all the time. They don't really tend to look ahead. So, they could possibly be affected much worse than gulls are, but we can't use these tags on gannets and that's because they're diving birds. They pht the water at 60 miles an hour. If they've got a harness and a tag on them, it could affect their behaviour and probably break the tag. So, we don't know.
Chris - Scientists in Saint Andrews have shown this week that seals change their behaviour because when you put these wind turbines in, they build a sort of artificial reef to put them on.
Viola - That's right, yeah.
Chris - And the seals, they can see by following the seals where all the wind turbines are because they spend all their time around them and they're saying actually, this could attract fish and other species around these artificial reefs. It may be that the seals make a beeline there, if that's the right phrase to use
Viola - A seal line, yeah.
Chris - But in fact, that means that you could decimate fish populations because all the fish go there and then they're easy pickings. Do you not think the birds might be impacted?
Viola - Yeah, it's really complicated. Well, I know people speculate that cormorants might be using wind turbines exactly the same way, but it probably isn't the case for other birds. I know eider duck for example, you can see that they start avoiding wind farms. 2 km away, they start making massive avoidance movements which means they're not using an area of the sea that they previously did use. And that could be having negative impacts on that population. We don't know yet. It's quite a complicated area really. These are just big birds with smaller birds and little storm petrels or even non-seabirds, migrating passerines just flying over. We don't know. They'll probably just get chopped up. But it's hard to test that yet. These tags are too big to put on them.
Chris - Who's got some questions?
Jeremy - My name is Jeremy. I come from Little Thetford.
Chris - You're not from Godmanchester. That's a good start.
Viola - I come from Big Thetford.
Jeremy - How do you catch the birds?
Viola - The way we catch them, well at least when we're tagging them - it's a good question - is in the breeding season, seabirds tie to their nests so they have incubate their eggs and they have to look after their chicks. The rest get out to sea and we probably couldn't catch them. But that means when they're on the nests, we can put a trap around the nest. It's just a wire mesh trap and the bird just walks and sits on its eggs. Acts like nothing has happened and then I come running out of the bushes and grab it and put it in the sack, and then go and put the tag on it and then let it go about 10 minutes later, and then it goes back to the nest and it's all fine. The colony gets wise to it after a while. You can easily trap 10 birds or whatever in the first few hours and then after that, they see me coming and they fly up straightaway. But if I wear different clothes, they don't know it's me anymore. So, I have to keep outwitting them.
Chris - It's interesting you disguise yourself because these guys in America were looking at mocking birds and they found that these mocking birds could tell one person who went and annoyed. If one of the researchers went and made annoying noises to their nest on a daily basis, they very quickly wised up to the fact that this guy was nuisance whereas the other guy from the lab who looked a bit different, they wouldn't object to him being near their nest. But the other chap, they would start attacking. So, they're obviously quite good at recognising individuals. So, you've made one or two enemies out there.
Viola - Definitely, yeah. It's not always a good thing to make an enemy of a gull. They come, they pooh all over me. It's really not very nice, but I probably deserve it, but all in the name of science.
Claire - Hi. I'm Claire and I work at the Cambridge Science Centre. My question was about great auks. When did they go extinct and what were the pressures on that species?
Viola - They were hunted to extinction. I think it's quite sad really. I think the last few auks were basically - people knew they were going extinct and it was almost just like a Victorian trophy thing. I can't remember the exact year the last great auk went extinct. It was 18 something. It's in the Victorian times, so it wasn't that long ago. Yeah, people were just going out and shooting. A lot of sea bird populations went down massively at that time including gulls and gannets. It wasn't just hunting. People were taking their feathers for hat making, and people were egg collecting. It's different attitude altogether.
Ginny - So, do you like going to the beach despite the fact that the gulls attack you?
Viola - Yeah, I love it actually. It gives me a whole extra dimension on the experience.
Ginny - What about building sandcastles? Are you a fan of sandcastles?
Viola - Yeah, everyone love sandcastles, right?
Ginny - Exactly, so we thought we would see if there was some science behind building sandcastles and see if we can make the best possible sandcastle here at the Cambridge Science Centre for you. Does that sound good?
Audience - Yes.
Georgia - Okay, so we've got a desk completely covered in sand here. What's this set up, what are we going to be doing?
Ginny - So, we're going to be looking at how much water you want in your sandcastle. So first of all, in this rather heavy box here, I have some lovely dry sand. So, you can see that's sort of flowing down from my fingers when I pick it up. It's bone dry. What do you think it was going to do if we make a sandcastle out of it?
Georgia - I imagine that will tumble down, much like a sand dune.
Ginny - Should we give it a go?
Georgia - Definitely.
Ginny - Okay, so I have a little kind of cup-shaped thing here. it actually used to have bay leaves in it and we're going to use that as our mould today for making a sandcastle. So, I'm going to pack it full of this really dry sand, pat it down and then I'm going to turn it out and we're going to see what happens. Here we go...
Chris - Woah! That's really good.
Ginny - What happened?
Child - It didn't stay up at all. As soon as it went out of the container, it just tumbled onto the floor.
Ginny - Yeah, so I definitely wouldn't call that a sandcastle, would you?
Georgia - No.
Ginny - So now, we're going to try a really, really wet one and see what happens there.
Georgia - Okay, so we're pouring in a mug of water into a very small amount of sand, so it's looking a bit more like gloopy mud at the moment rather than sand, we're just mixing it together.
Ginny - Right. So, I'm going to try and slop some of this stuff into my tube. It's feeling pretty wet, but we said we wanted water to make a sandcastle, didn't we, we said we needed it nice and wet.
Georgia - What do you guys think is going to happen?
Child - I think it's going to be too wet and then it will all fall out.
Georgia - Just packing the end of the sand in.
Ginny - three, two, one... It seem stuck. It came out earlier, eventually.
Chris - I think we can conclude that that's not a good recipe either Ginny.
Ginny - Okay, here we go.
Georgia - Well, it's come out in bits. It's not quite what you'd want at the seaside.
Ginny - But it is at least sort of standing up. It's sort of a sandcastle, isn't it guys? So now, to see how good a sandcastle it is, we're going to see how much weight it can take. So, we're going to pile some pound coins on top and see how many we can get on it - one, two, let's go in two's now, four, six, eight - it's not doing badly, is it? Ten, twelve, fourteen - oh, I saw a bit of movement.
Georgia - I need some more pound coins.
Ginny - Sixteen, eighteen - this is much better than I was expecting - twenty, twenty-two, twenty-four, twenty-six - I think some of the water drained out of it while we were trying to get it out.
Chris - You're going to move to a country where the exchange rate is a bit better, Ginny.
Ginny - Wow! I think my pound coin tower might fall over before my sandcastle does. So, we've shown that for strength at least, you want your sandcastle to be as wet as possible. Well, I think our sandcastle deserves a round of applause.
Chris - So Ginny, why does adding the water make it stronger and stick together better?
Ginny - Water is really interesting because it has something called surface tension. So, if any of you ever filled a glass so full that it looked like it was going to spill over the top? But then you realise that actually, the water is sort of sticking up over the top of the glass in a kind of curve. Have you seen that? I've got lots of nodding. So, that's because it's something called surface tension. Water molecules like each other and they like to stick together and hang together. So, when I've got my dry sand, there's nothing to make it stick together. But as soon as I add some water, the water wants to hug itself. It wants to grab the sand molecules and it's going to keep them together. It forms kind of little bridges between the sand. What you want is you want enough water that it's going to fill up all the gaps between sands. So, if you only have a little bit of water, it's not going to fill all of those gaps. You want enough to fill all of those gaps, but not so much that the water itself starts to flow and become a liquid and you just got water with some sand in it. So, getting that proportion just right is what makes a really good sandcastle...
32:59 - Coral reefs and climate change
Coral reefs and climate change
with Mark Spalding, Conservation Science Laboratory, University of Cambridge
Coral reefs all over the world are being affected by climate change. Mark Spalding from the Conservation Science Laboratory explains how and why to Chris Smith...
Mark - So, I work for an organisation called the Nature Conservancy. They're not well-known in the UK and our mission is to look after the lands and waters which all life depends. That's what we're setting out to do and we're an organisation that works around the world, 35 countries in the sea and on land. My work is focused very much on marine habitats. I guess my passion for the sea started probably at pretty early age actually. I was, I think 11 when I first dived on a coral reef and I don't think I ever really looked back.
Chris - Why are coral reefs important? Why do we regard them as really important for conservation?
Mark - So many ways. So, coral reefs are these wonderful rain forests of the sea we talk about. They're mega diverse habitats that are built many of the tropics where they kind of circle the land and they're highly productive. So, they're wonderfully important for many people who rely on it for fish. They also actually produce many other benefits - so, they protect our many coasts from the impact of waves and many tropical countries of course, you've got hurricanes and things that threaten coasts. So, that's tremendously important. Someone asked the question earlier about some of the chemicals and cosmetics, and products that we might get from the sea. Well, coral reefs have been seen as - because of their immense diversity, it's potentially really important sites for providing new pharmaceuticals and new compounds that we might use in all sorts of ways. Already, products from coral reef animals are being used in some drugs for cancer, and in sunscreens as well actually strangely enough, and there's much more to be found.
Chris - Tell us about the sunscreens. I'm intrigued. You rub bits of coral onto you?
Mark - No, it would be pretty painful I think. No, but corals are actually dependent on light, which is why we get them in bright sunlit waters and because they're dependent on light, they're also subjected to quite a lot of UV light which just as it can with us, can cause problems for the coral. So, they've developed some mechanisms to defend themselves from UV light which we've then been able to utilise.
Chris - But how do they rub it on?
Mark - A lot of these things, we look to nature for the inspiration and then the scientists then work with compounds that we're finding in nature to build the properties that we might want.
Chris - Why are coral reefs regarded as threatened?
Mark - Well, if you look at the reefs of the world, they're spread out in a soft of belt around the tropics. They've adapted to live in an environment which is pretty stable year-round, fairly stable temperatures, and they have adapted to that extremely well. What's happening now is that we're starting to see already slight increases in the world's temperatures and the sea water temperatures as well. And it turns out that corals are extremely vulnerable even to the smallest changes in temperatures. So, an increase above the normal maximum of a degree or two for a few weeks will cause a stress response in corals.
Chris - Do we know why they're so sensitive?
Mark - Only that they've seem to have adapted. We don't know enough to be quite honest, but they seem to have adapted to this sort of lovely year-round Jamaica kind of temperature and can't cope with a bit more. They have a very complex relationship inside their body tissues with an algae, which uses sunlight to generate energy which the corals use. They're almost photosynthetic as organisms. When they get too hot, the algae become expelled. The coral go white and we call it bleaching. At that point, they're starving. They're still alive, but they're not getting any food anymore. If it continues for even just a few weeks, the corals will perish. At that point, the reef looks pretty dead. They can come back of course once the temperatures cool down, but those corals are dead.
Chris - What is the scale of the problem if you look around the world at the reefs we've been monitoring?
Mark - People first noticed coral bleaching probably 20 years ago, but there was no extreme events. And then in 1998, we had an El Niño year which is a Pacific Ocean climatic phenomenon and an oceanographic phenomenon, but it essentially drove warm waters around the world. It was the most extreme el Niño we'd had. I happened to be doing an expedition at the time in the Seychelles, looking at the coral reefs across the Seychelles, hoping to have this wonderful time diving on the world's most pristine coral reefs.
Chris - A holiday.
Mark - Yeah. There was a good report at the end of it! That's the difference. It was wonderful. We were on a yacht, sailing down the Seychelles. But as we got there, we saw that the corals were all bleaching and it was actually really depressing to do a 2,000km transect through the Seychelles Islands and watch the coral reefs in the Seychelles die. And as we came back, we heard the news from the entire Western Indian Ocean, that it was the Maldives, the Seychelles, the Chagos Islands, and so on, huge areas of coral reefs had all, 90% of the coral reefs had died that year.
Chris - That's a new thing. do we think this is a worsening trend or do we just think there've been blips like this in the past and that this is just another one and it will get better.
Mark - No one had seen anything on the scale of what happened in 1998 and it is increasing more frequently and more extensive. There hasn't been anything to parallel '98, but unfortunately, omens are pretty poor for next year. It looks like there's another big el Niño brewing, so it looks like we'll see another of these events. The real concern from the scientists is that corals are not going to have enough time for the evolutionary adaptation that they might need. And as temperatures warm up, these events might become more frequent. And so, they won't be able to recover in between these events. So, it's a very worrying time for coral reefs.
Chris - Can we do anything about it?
Mark - We're not sure. There seems to be some evidence that corals themselves are doing something about it that the corals that come back are a little bit more robust. My organisation is doing some pretty interesting stuff in the Caribbean coral reefs where we're trying to grow and we've got nurseries, just like you might see plant nurseries with tens of thousands of corals being grown up underwater. And we are selecting them for the resistance to bleaching and we're starting to plant them out on the coral reefs of the Caribbean. So, we're trying but really, we're pretty worried about the state of coral reefs worldwide.
Chris - But the benefit is, they don't wake you up at night, do they, your corals in your nursery?
Mark - Yes.
Chris - Any questions so far for Mark?
Emily - I'm Emily and I was wondering how poisonous coral stings are.
Mark - Emily, great question. Well corals, if you look up closer to coral, it's made up of lots of little, small organisms living in a colony and those small organisms, just like sea anemones, they're exactly the same group of animals of sea anemones. They have, all of them, the capacity to sting, they have a little special adaptation in nematocysts which enables them to sting. Now, most corals couldn't sting a person or you wouldn't feel it. There's a few corals that do sting and it's a little bit like a nettle sting. Not that bad, but a few people are allergic to it and some people are found that the more they get stung, the worst their reaction is. But generally, not that bad.
Chris - Anything else? Georgia, what have you got?
Georgia - I have a question about that. In Finding Nemo, the clown fish swims around...
Chris - That well known documentary, yeah!
Georgia - The clown fish swims around the coral and it gives him more of an immunity to stings, but it's the other way around for humans.
Mark - The observation is exactly right. It's an anemone of course that the clown fish lives in, but as I said, they're related to corals. And yes, they do seem to develop an immunity to the stings which other fish don't have. And I believe it's something that builds in on the mucus on the surface of the skin of the clown fish. If you take a clown fish out of an anemone for long enough, it will lose its immunity and if it goes into the anemone, it will be stung and it will be eaten. So, when a clown fish meets an anemone, it spends a bit of time adapting and just touching the edge of the anemone until it develops its immunity.
Chris - Is that like sort of graded drinking where you get a few minor hangovers but you build up a tolerance?
Mark - A little bit like that, building up a tolerance.
Chris - Any other questions?
Georgia - We also have a question from Twitter. Oren Jello wants to know where coral reefs can go. What stops them from growing everywhere?
Mark - That's a really good question too. Climate change is already on us and I think we need to get that clear. So, as temperatures are warming up, a lot of species are already changing their distribution. We see that in UK waters. I'm sure you've seen it with the birds. So, we're already seeing that and corals are moving too. But as you move out from the tropics, you get a slightly different sort of a climate because you get much more seasonality outside of the tropics. So, I said to you at the beginning, corals are adapted to this lovely, sort of wall to wall Jamaican type temperature year-round. As you move out of the tropics, you get cold winters and that's quite tough. Corals don't like the cold either. So, they've kind of adapted to this. So, it's not a given that corals can migrate further north or south out of the tropics. But we are seeing some movements in those directions.
Chris - Lloyd.
Lloyd - It's really interesting, but if you look at animals that live in stable temperature environments, so the two places in the sea where the temperatures are very stable are in the tropics and the poles. Animals living there have very small abilities to survive when the temperatures warm up. So, there's been a fair bit of experimentation looking at those temperatures they can survive with and they're literaturally maybe a couple of degrees over their normal temperatures. They start to die. But if you look in-between where the temperatures are variable in the sea, in the temperate latitudes, the cold temperate latitudes, warm temperate latitudes, they have maybe 6 to 10-degree buffer over the top of what they normally see that they can survive. And it looks like it's this exposure to variability of temperature in the environment that gives animals the capacity to survive a warming environment that isn't there when they live in very stable conditions like the tropics or in the poles.
Mark - So, you're seeing that in the Antarctic as well, are you?
Lloyd - Absolutely and there's been 2 or 3 pieces of work published on the same groups of animals from the poles to the tropics. And the polar and tropical animals both have the same limit in terms of their ability to cope with the warming and the ones in-between have a much, much higher ability to cope with the warming there.
47:23 - Whale dandruff reveals family ties
Whale dandruff reveals family ties
with Bill Amos, Cambridge University Department of Zoology
Bill Amos explains to Chris Smith how DNA from whale dandruff holds the key to unlocking their family dynamics...
Bill - My career is rather serendipitous in that I did my PhD on the genetics of green fly, and it wasn't a very successful study! I was wondering what to do next and I went to an inspirational talk by a guy called Alec Jeffreys, who was the guy who invented DNA fingerprinting - this way of identifying individuals and working out who's related to who, using genetic techniques, using DNA techniques. I thought this was fantastic and I came back to Cambridge and I met this odd guy walking down the street with a bandana on his head. I knew he was the weird guy in the department who disappeared for most of the year and he was a sailor and his whole research was on the behaviour of whales. He asked me, he said, "Look, we've got some material. We've got this study that we'd like to do some genetics on whales, but we don't know what to do." I said, "Well, I've got the best technique you could think of." Basically, I've never look back. So, I started off two projects: one on the grey seal up, in Scotland, and one on pilot whales, which are hunted in a traditional fishery in the Faroe Islands; and in both cases I was using DNA fingerprinting to work out who's related to who.
Chris - And not who done it?
Bill - Not who done it? Well, slightly who done it as in who's the father on occasions, but yeah, we were trying to find out something about the ecology of these animals because of course, if you go to sea and look out at the sea, you see an awful lot of water without any whales in. In fact, if there are any chemists out there, I once worked out that the sea has a concentration of whales of about 10-38 molar. So, it's a very, very dilute solution of whales!
Chris - So, two questions then - one, how do you find the whales, and, more importantly, how do you find out their genetic code? What do you have to do?
Bill - Well, first of all, you need to get some samples and in the Faroe Islands, they were hunting the whales. I really hated being involved in this project, but it was an unusual circumstance and the whales, we're going to be dead anyway. But normally, you don't have that as it were the luxury of access to those samples. So, we were looking for other methods and at that time, there were people developing methods based on bows and arrows. You go into the boat with a bow and arrow and on the end of the arrow would be a tiny little - like an apple corer - which was capable of taking little plug of skin with a rubber bung to stop it hurting the whale. So, it just go bump and take a little plug of skin and you have it on a fishing line then you'd haul it back in. We decided to go down a less invasive route, slightly more difficult, but a bit more glamourous. So, we realised that whales actually shed skin like we have dandruff. But of course, they have spectacular dandruff on occasions.
Chris - Define spectacular.
Bill - I've seen pieces of whale skin about a meter square like a little chiffon scarf sitting in the seawater.
Chris - How would you recognise it? What does it look like then?
Bill - They're just little fragments of dark material and it depends what the whale has been doing. If you're lucky enough to see a whale breech, that's when they leap out of the water and come down with a huge splash then you can actually smell the skin on the surface of the water, and if you dive into the water with a little aquarium net, if you get there before the fish, because of course, this is a bit of a source of food, you can scoop up bits. Now, the nice thing is, that whales, you can identify them individually from the patterns of natural markings. They accumulate scars and so, you take a photograph of the whale, you then follow it in the water, and as soon as it dives, the turbulence of the water around the tail when it dives means it sheds a bit of skin into the water and you then dive off your boat, and you hope to find some fragments that you can then link to that individual.
Chris - And you can get the DNA out of those cells?
Bill - Those bits of skin are big enough to get nice DNA out of. And a student of mine working on humpback whales ended up with 650 individually identified animals and then you can start asking interesting questions because really, we don't understand much about the humpback whales' social organisation. There are a lot of documentaries, but most of the science in terms of what they're actually doing and why, really remains to be found that...
Chris - How do you actually use this because the whales are going to hang around in groups, aren't they? They're social animals. They like to be together. So, how do you not know when you scoop up your whale skin with your nets that you're not scooping up a bit of me, a bit of you, a bit of this guy here?
Bill - Fish are very good at hovering and keeping the water pretty clean. So, you usually follow an individual and when it dives, you collect the skin from that. Now, where we were working and I only got to go there once, but it was wonderful. Two weeks of miraculous experience of swimming with humpback whales.
Chris - It's all for the science.
Bill - I've had quite a long career and I've spent 4 weeks actually swimming with whales. In Hawaii, the whales are sensible. When they want to reproduce, they swim to the nice warm waters around shallow, generally equatorial islands like Hawaii, like the West Indies, places like that, and the females give birth. And then the female and her calf will stay together for a number of weeks suckling before they return up to the much richer waters up in the arctic in the northern hemisphere and the Antarctic in the southern hemisphere where they really feed up during the summer on huge sholes of either crustaceans or fish, depending on the species. So, we can follow the mother and her calf, those are together. Sometimes they have an escorting male, we still don't know why the male hangs around with the female, whether he's waiting for mating opportunity or whether he's simply maybe the father of the previous year. In fact, we disproved that genetically. He certainly isn't the father of the previous year. But on the other hand, other males will sit there singing. You've heard of the song of the whale and it's amazing. You can actually hear this song above the water. So, you're on a boat and you hear this amazing (makes a whale sound) incredible sound coming...
Chris - He deserves a round of applause for that. [clapping]
Bill - These guys sit there 30 foot down, making this incredible sound and each male has a different song. And we really don't know why. Occasionally, another male will come along and perhaps challenge that male and then sit in the same place singing his song. But nobody to my knowledge has ever seen a female visit the male and mates with the male. Maybe they're just amusing themselves. We don't know.
Chris - So will the ultimate aim then, you're going to follow these guys and then do these genetic testing to see if that male ever does end up a father of next year's calf and it's just that you end up with a sort of escort, escorting someone else's baby, but with the aim to mate the next year?
Bill - Absolutely. Well, we're interested in any kinds of relationships there. The other group that seems much more oriented to mating is called the rowdy groups, which is a bunch of males who all seem to be fighting for position near to a female who we kind of assume is fertile and is able to conceive at this point. They're really violently -you may have seen documentaries of them slamming into each other. Again, we really don't know who's the winner, whether any of them are the winner. Maybe the female just finally gets rid of them and goes and chooses the male she actually wants as a partner. So, these are big questions and you can answer them genetically.
Chris - Any questions for Bill?
Kasian - My name is Kasian and my question is, you said that when whales swim, their skin comes off. Well, how does their skin come off?
Bill - Well, it's just like people. The skin is the layer that separates you from the environment. And the environment is harsh. It's got sunlight coming down. You might get sunburn. There is a theory that even whales get sunburned - believe it or not - if they stay at the surface too long. So, one of the defences that all animals have is to keep shedding the outer layer and keep replacing it from underneath. So, if you cut your finger, you don't have a cut for life. Soon, the skin grows over and mends that cut. So, it's constantly replaced. When does it come off? Well, it comes off a little bit all the time but if you suddenly move and you're a whale in the water, then you shed a bit more than you would do normally, and that's when you find the bigger pieces.
Chris - Georgia...
Georgia - What happens to all the barnacles and things that live on the whales when they shed their skin?
Bill - Some whales, not all of them, but some species have barnacles which live on them for varying lengths of time. You may notice the right whale - ironically, it's called the right whale because it was the right whale to hunt, and it's the right whale to hunt because it's the only whale that floats when it's dead. And if you just harpooned a 50-ton animal that sinks and you're in a small boat, you haven't done yourself a lot of favours. So, the Right whales have these crusts on the front of their faces which are white and crusty and those are barnacles, and they stay on for life as far as we know. They clearly have evolved mechanisms for staying there very thoroughly. Mostly, animals that try to sit on the whale and use it for something to grow on are shed pretty rapidly. Whale skin is very dynamic and they're capable of losing any unwanted passengers.
Emily - I'm Emily and what if you get hit with the fluke of a whale.
Ginny - Can you just tell us quickly what a fluke is?
Bill - The fluke is the name you call the tail of the whale. The fluke of the whale, particularly the big whales is a huge weapon. They use it against each other. They use it for signalling. If they hit a diver with it, that diver would not be a diver anymore unfortunately, he'd go into the marine ecosystem. So, they're very powerful. I don't know if you've seen a film of it, but one way killer whales hunt fish is they school them into a big ball where the fish don't know what's happening and they're milling around in what looks like a glitter bowl of fish swimming around. One of the whales will come in and smack the ball hard with the tail and it's so powerful, you'll see the water is suddenly full of all these stunned fish. So, it doesn't have to swim after them and just hoover them up where they are, so it's very powerful.
Bob - Hi. My name is Bob. Can you say roughly how much genetic variation there is between members of the same species of whale or between whale species and how much there is in common between human DNA and whale DNA?
Bill - There's a lot of variation in whales and there's a lot of variation between the species of whales, such that you can use genetics to identify not only different species of whale, but also, which ocean they came from. I've been asked to do some work in the past when they got suspicious shipments of some kind of meat and they wanted to know whether it was an illegal species of whale and I did some genetics and I was able to tell them that the particular shipment was in fact minky whale meat which the smallest of the baleen whales with the big throat pleats. It poorly came from the Pacific Ocean. That made sense - it was a box from the Far East. In fact, the reason they were suspicious, the customs officer said, "Well, it did have whale meat in large letters on the outside." So, I guess that raised their suspicions. In terms of the difference between humans and whales, there is plenty. Clearly, we're very different to look at, but we know that we are 99% similar to chimpanzees. So, if you get a stretch of a thousand of your DNA letters, then only 10 of them on average will differ between us and chimpanzees. Between whales, it's probably more like 2 or 3%. But it's not massive. The genes are entirely recognisable. Actually, mammals aren't that old in terms of the divergence of the DNA. What matters is how the genes have changed very subtly. Don't forget that if you get one mutation, you might have a really nasty disease or one mutation might make your eyes blue as opposed to brown. Small changes can make a big difference in genes.
Scott - I'm Scott, I belong to Emily. My question is actually for the entire panel. I'm sure there's tons of young aspiring marine biologists out there. What would be the one bit of advice you would share with them, I guess early on?
Bill - Passion gets you a long way. If you're really bright, that's great because some of the academic stuff is tough but there are niches in which most people can work: some people are really good at organising and chatting to people and they can do fundraising for conservation; some people are really good at writing, they can go into science journalism. So just be passionate about it. Ironically, at school, the one subject I really hated was genetics and I actually chose my degree course to avoid doing genetics. But actually, when I started doing the degree, I did some genetics and I thought, "Wow! This is cool." You suddenly see something, you get the inspiration, take hold of it.
Chris - Mark Spalding, what would you say?
Mark - I second the passion thing. I think if you've got the passion, it will take you a long way. I'd also really say if you can get experience wherever you are, even just getting out and volunteering with people with organisations, going along the university and say, "Can I help?" this kind of thing, it sets you out of the crowd because it is quite a competitive field to find work, but enjoy it and get experience.
Chris - Viola.
Viola - Yes, that's basically what I was going to say, get out there. Get experience, do some volunteering. Go along to things like a bird ringing demonstration for example if you just want to see what these things are like. I think field work is really important to energise your passion if you have it and help it grow.
Chris - Lloyd...
Lloyd - I'd say, don't be afraid of asking questions. If there's something you're interested in then ask questions about it, find out about it, and don't be afraid of chasing a dream, just follow that dream down...