[Music]
hello and welcome to technically speaking where scientists and Engineers come together chat a common interest share knowledge and satisfy some curiosity I'm Laura and I'm joined by Jasmin and Ellie to talk about sharks and bust some Sharky myths Jasmin what's your favorite shark myth my favorite shark myth is related to fighing Nemo which I think is a great movie that involves sharks and other Aquatic animals so there's like a famous scene in the movie Dory injures your and
like ends up bleeding and then Bruce who's the big ball shark he gets a sniff of the blood and then goes into a complete frenzy and starts trying to eat Nemo and Dory are sharks attracted to blood and how far away can they smell it cuz apparently like it's like smell one drop of blood from like a mile away or something is what people say oo yeah I have heard that too and I query it so I did some digging which I guess we'll get into later on cuz I went down some weird
rabbit holes um my math is OD [Laughter] Ellie you're a zoologist and you now work in science communication for a big science news Outlet so what do you know about sharks well I wouldn't say quite a lot but I would say more than the average person I'm a bit of a shark Advocate I feel like they get a bad rep that they don't deserve a bit like snakes and spiders I think they're pretty cool and I think there's a lot of people don't know about sharks actually and rats oh also I learned especially
for this podcast that there are more than a thousand species of sharks and Rays wow which I think is cool and more get discovered every year because some of them live very deep in the ocean and we don't necessarily see them wow but sharks and Rays get grouped quite a lot because of zoologist taxonomic reasons but sharks I think like the accepted standard is about 500 species which is still loads if you say shark to me I just think of Jaws essentially CU that's the the popular one isn't it oh you
can't just love and pull sharks together Laura I know sh is famous and uh you know everyone's got the dir dir in their head forever but there's more to sharks than just the great white I'm sure there is and I guess that gives us a lot to go at for this conversation but I think we should start by busting the blood sniffing myth that Jasmine mentioned should we do that yeah yeah cool so I said I did some maths I trust your maths a lot more than mine oh when you hear the numbers you might say
no so the starting point for this is one drop in a billion and this does seem to be based on a scientific paper where they um they essentially got a shark in a tank and held I'm I'm probably misremembering this but it kind of held something that held some sort of scent close to the nose and figured out what the dilution factor was and just kept reducing the concentration until they knew the shark couldn't detect it by putting sensors on the shark somehow I'm garbling that terribly but isn't the
point so they did it like in a controlled environment like they had the shark in a tank sort of thing and they I guess added less scent or more water to keep diluting it yeah less scent and then they worked out what the dilution factor was and they were like waiting for the shark to swim towards the blood or something I think the shark was held in position so what what they came out with was um it was in moles per liter which roughly someone translated into like one drop in a billion so one part
per billion that does vaguely ring a bell from chemistry way back when yeah so it's of certain scent molecules and the one that I think is most close related to blood is I think they were using amino acids I assume you do have those in your blood going back to our earlier podcast episode about what even is meat oh yes so one drop of an amino acid in water how does that come into being able to smell it from a mile away I don't think it does oh God I suppose you
can't quantify how much water there is in a mile of ocean can you like that well if you assume the water isn't moving for a start so you're just in this confined sphere say you're the middle of this mile radius sphere you would need something like 17,000 lers of blood to meet that detection limit of a part per billion wow yeah that's that's that's a lot more Blood Cuz you know you watch those silly movies don't you and she like cuts her leg dramatically on a rock and then the
shark is immediately circling her trying to get at her yeah like it suddenly come from out of nowhere like they detected it yeah obviously this is in a mile sphere and you're not going to be a mile underwat but even half that you're still thousands and thousands of leiters of blood way more blood than it was in the human body it must be almost instantly way too dilute I think the only way like a shark would actually be able to detect human blood is if it s just happens to
be near a human that's and even then it's not necessarily that it's interested in the human it's just like it smells something it's like oh what is this I will investigate probably yeah I did do a calculation another way and found out what the drop of blood used in fing prick test is which is 35 microliters thank you Boston University and for that dilution factor the shark would need to be two meters away to detect it and of course the the blood still has to diffuse out I reckon
I could detect it if I was 2 MERS away yeah it's still not blood it's seeming a m in the blood would be more than 35 microliters of blood to get the amino acid in there I think we can consider that myth busted to be honest I think even if there were currents and things involved that were transporting the amino acids or the blood to the shark there's still a Time factor involved I reckon you'd be long gone by the time the shark smelled it and then came to investigate yeah also if you're bleeding
in the ocean presumably you're going to get out aren't you unless you're traps and also I don't believe that sharks go around detecting like fish from blood do they not really no it's not a typical thing they're like there aren't loads of flish bleeding in the ocean that the Sharks then immediately going for it doesn't work like that but there was a ex NASA engineer or scientist who did an experiment I think right in quotation marks cuz he basically like had fish
blood versus I think it was sheep's blood BL and he was like seeing what would attract more sharks and the non-fish blood basically attracted no sharks but the fish blood attracted quite a few sharks well that makes sense I I'll give them that yeah cuz sharks have been evolved to like want to eat fish cuz it's one of their main food sources also sharks are fish we should make that clear yes cuz people do get confused they're not M yeah they're not like dolphins need to come up to get air
they can breathe through their gills is a word I'm looking for I could see your mind wearing then I was going to say breathe through their LS that's how most cre breathe but yeah I guess the point about they would only tend to react to certain things makes a lot of sense and there are probably things that they I guess they can't smell it's like the difference between humans and dogs is I would think of it my dog which went wild over some scent before and I took him
for a walk and I had no clue what he was doing yeah that true that's very common like the general consensus of like whether or not sharks are really good at smelling versus other fish it's bit confusing cuz apparently sharks do have really good sense of smell but other sources will say it's about the same as pretty much any other fish I don't ever think of fish smelling stuff like part from the whole shark blood scenario that's literally the only example apparently fish you smell as a way of
like detecting if there's Predators nearby or if there's like a potential mate nearby but not food Strangely I think in the ocean it confuses me like you know dogs we on lamp posts and that sort of thing and it lingers much more frequently than but in the ocean it's so mixed up constantly that I don't imagine sense work the same way if you're just smelling something on a breeze or a current would you necessarily bother pursuing it yeah it could just be you know like when you
walk outside and you smell someone's curry cooking you just sort of smell it and move on don't you but also generally the ocean smells really bad to you or to a fish well to humans it smells really bad cuz I was at one of the SeaWorld things or like something similar to a SeaWorld and the turtle like went to the surface and when it emerged there was like a giant waft and it absolutely reached that's an artificial environment that's not the ocean kind of suggest
that animal wasn't looked after very well remember the ocean is also the fish's toilet so I mean a lot of our sewage end up in the ocean so I don't think we can really blame it all on the fish no so if we're going with this idea that you probably can't really smell a great deal of anything of interest in the ocean because of all the stuff that's being put into it yeah what would be a more sensible sense that sharks would use like is their eyesight better and therefore more reliable apparently
sharks have surprisingly good eyesight they can distinguish colors and they apparently have like quite good depending on a type of shark quite good like dark vision slight Vision sharks also have really good hearing they do tend to use sound quite a lot so if they can hear like splashing then they're more likely to investigate especially from like great greater distances yeah I think shark's very sensitive hearing actually and especially like low frequency sounds okay so if I'm swimming
in the sea near me which is quite likely because I live I don't know like a mile from the sea I do it quite a lot and there's a shark around what should be my tactic do I just kind of be still and Float on the surface and hang out until it goes away or do I swim like mad to get out there I think most of the time they're not going to approach you if you don't bother them so I think probably swimming slowly away in a non you know like not panicking might be your best
bet but I don't know what the official advice is if that you're you know cuz of like scuba divers and stuff if you see sharks what you should actually do I I wasn't taught that when I learned scuba di I only did it once or twice so that's I don't think I really needed to know I was always with someone I think they say also try not to uh resemble a seal like try and stay vertical like so you look slightly weird they like don't dive or anything like that oh I had
heard that they're attracted to people on surfboards because they look a bit seal like from below with the outline it's the round plump shape oh otherwise I'm not sure I look much like a seal in any configuration this uh Australian advice Forum says reduce risk of being bitten by a shark are to avoid swimming after dusk during the night or Before Dawn don't go swimming alone so maybe it's more about the time of day is that got something to do with a night vision that
Jasmine mentioned yeah it could well be it could be more um likely to go hunting at night I don't know I guess it depends on the shark species okay so then continue my tactic for swimming with the sharks theme yeah a lot of people use a cage to go swing with sharks right but if you're not doing it at night given everything we said previously do you really need a cage or would you be fine to just hang out Don't splash around too much don't dive I think the thing with
the cage is that it's better safe than sorry right because the cages are almost exclusively used for great white shark diving in places like South America uh South Africa not South America I don't know if they still do it quite the same way but at one time there was suggestion that they attracted the Sharks to the people in the cage by throwing meat into the water and then the Sharks would think oh I'll go that way cuz I can smell it but not from that far away then
having people in the water with a shark that potentially just smell food might not necessarily be the best idea but you couldn't guarantee that the shark would attack you either way but if you're in a cage then you are obviously protected and great white sharks are massive apex predators so if they chose to take against you you wouldn't necessarily survive there's a movie called Nia that's on Netflix right now and it like follows a woman who swam all the way
from Cuba to Florida me she actually did do it without a shark cage mhm uh because she found that with the cage it was like harder to swim they had to come up with another way to deter sharks and they ended up using like electromagnetic current I think because they have like a six sense don't they yeah it's called the oh is it the UL of Lorenzi I should really remember this for my degree it's something like it's got a fancy name it's the uler of lenzini lorenzini
something like that which is essentially an electro sensory system so they can detect electrical fields which is really cool including like muscle contractions in prey isn't that so fun and also they use the geomagnetic field of Earth to like orientate themselves and navigate the oceans oh that's pretty cool Incredible it's so cool yes this is this is the line that we need to be on is that sharks are really cool and we don't have any Humulin hum I can't speak today any human equivalent
of this sort of like Electro reception which is a shame I think imagine if you could right do birds also have the same thing cuz I'm wondering if like that if they use it for like when they migrate I think they have some awareness of the geomagnetic fields of Earth but I couldn't tell you for sure and they definitely don't have these like actual it's like paws on the mouth of the shark or like nose the underside of the nose of the shark uh which birds definitely
don't have cuz they have beaks obviously you said the sentences are on either side of their not so when I was reading into what they can smell they found that the sharks can sense the direction of smell because they have like different scent receptors in different parts of their base I guess yeah I guess that might be the same for the electrical receptors as well I'm not going to try and repeat that word that you said um I guess so I wouldn't know definitely for every shark where they
were on but it's like the ones I've seen diagrams of if you imagine the pointed nose of a shark they're like under the nose so they're in I guess one area but then slightly to each side or they can obviously swim around and see if it's stronger in one way or the other you've also got me wondering whether that is more sensitive than the sense of smell I've not seen any research to say either way which is better and I guess it depends on the Shar right CU different
sharks got different niches to fill exactly different sharks hunt different things so something like a hammerhead would hunt often like Rays or things that are buried under the sand so they are really relying on the electro reception because they obviously can't see the thing but if you can detect changes in like muscle contractions of array buried under the sand then you're going to be much better at hunting which is pretty nifty so I guess going back to my thing about the cage depending on I
guess what the cage is made of and what you're doing with it would help the track them which is maybe what you want yeah you're doing it deliberately aren't you cuz apparently trying to swim in a cage over a long distance doesn't make sense I can see why unless you're trying to break some world record or set a world record well yeah but you're not allowed to be touched when you're doing that and trying to do it inside a cage that you're trying not to touch and have
the cage keep paace with you because I assume it would be attached to a vessel a ship yeah that's why the woman in niad decided to swim without a cage and then use the electromagnetic method to deter the Sharks I wonder how much of the risk they really thought that was then if she had to have a cage in the first place like they must have calculated that that was was quite High I mean the stretch of Ocean between Cuba and Florida there are definitely sharks it's shark territory
but they're not that dangerous realistically I think I read that there were like 10 fatal shark attacks last year so apparently the Florida museum of natural histor International shark attack file investigated a total of 120 alleged innocent till proven guilty these sharks uh shark human interactions in 2023 and yes the Fatal ones I think it said there were 10 that goes back to what we were saying about they evolve to do particular things and we're not often in the sea with sharks so they've
evolved to hunt other prey they don't necessarily know what we are yeah that's true I mean we know what sharks are because we have the internet but it doesn't mean that every shark is going to be like that's a person I shouldn't bite them like it doesn't work like that well that's not a nice person I'm definitely going to eat that person because they don't do good in this world I'm doing it for the greater good of mankind of the planet yeah but yeah so this was the thing that
made me think like really how dangerous are they because I do risk assessments for my career scientist working in a lab and I used to be a nuclear safety consultant you normally look at what's the worst thing that can happen and How likely is that worst thing to happen 10 attacks in I don't know how many people would have been swimming in the water sounds very very low like you wouldn't really need to mitigate it that extreme I mean it's it's a risk so obviously
like in places where you have lots of people swimming that's also potentially or is an area where you do get a lot of sharks there will be like measures put into place to like try to prevent potential shark attacks but in comparison to like other ways that people get injured or killed um more people are killed in road traffic accidents more people are killed by being stri by lightning apparently more people are killed every year by falling coconut than they are by shark also if you don't
want to be killed by a shark don't go in the ocean they were there first well there that that is the Surefire way to not beaten by a shark yeah yep not being killed by a coconut though don't stand under coconut trees don't go where there are coconuts exactly I have done both lightning is just very unlucky I don't think you could well maybe you can actively avoid being hit by lightning just need to stay very low down wearing rubber boots the whole time live in a
faraday cage we're back to cages again the US leads again in the number of unprovoked bites so I guess if you were going to get attacked the states is the highest chance and Then followed by Australia I don't think that's surprising given the fact that they have more coastline and more sharks than anywhere else like the percentage is just higher right yeah but unprovoked as well what how would you do to provoke a shark like attract his attention and then annoy it and then it just bites you
insult its intelligence its ability to smell this episode is all about making friends with sharks not provoking them I think we should take a closer look at how sharks behave so what would it take to befriend a shark well we recently found out that sharks have friends which I think is adorable and the reason that we found this out is because there was a study on two great white sharks that were found to have traveled 6,000 km up the Atlantic coast together so each of
these sharks was wearing like one of those data tags they were named Jackal and Simon adorably and they appeared to have stayed together the whole time on this massive massive journey and they were both tagged in December of 2022 off the coast of Georgia and they went all the way up together which I just think is nice right cuz we don't think about animals necessarily having best friends and Pals but why shouldn't they and why why would they not be a little bit
social like it's quite lonely in the ocean yeah I'm surprised cuz I thought whites were solitary that is typically what is written in the literature doesn't mean it's necessarily true the Sharks don't read the textbooks as I was frequently told I guess Nature has some variety I wonder what led them to befriend each other then like what was the advantage well there is a suggestion that two sharks are better than one when it comes to eating things that you might
want to eat as a shark uh safety and numbers all of that sort of thing you mean they sort of work together to run prey down a bit like whales do or two noses are better than one yeah could also be like a safety security thing because orcas do scare sharks cuz orcas are bullies and have been known to hunt on certain sharks I think that's the only thing that would take a shark really like a big shark like a great white would be an orer there was a whole um Spate of oras killing sharks and
eating their livers which apparently are especially delicious if you're an orca oh even though they're an apex predator H yeah orcas are quite mean they also have to eat so we we for the of the ocean like there's an observation where there were a bunch of great whites in an Aira I think it was like off the coast of Florida part of orkers is that what it's called yeah I would go for that they were just like passing by and the Sharks sense that the orkers were nearby and they all
basically just swam away I'm scared of orkers and I would love to see one but I also wouldn't want to be in the ocean with one what you're telling me is to be friends with sharks and not with the orcus so free Willie was just incredibly misleading also they found that gray reef sharks hang out with the same friends year after year nice isn't that adorable so it's not just the great whites it's other slightly friendlier smaller looking species that also have mates I
think it's more like a semiotic relation but isn't there a type of shark where there's like another species of fish that's smaller and it just like eats parasites off of the surface of the shark skin so basically like gives it a bit of a clean that is almost certainly true because there's a lot of ocean parasites so is that a tactic for brending a shark then keep it clean it yeah why not yeah you see um videos of sharks sometimes with their mouths open and little like cleaner fish going in
and eating the debris not many dentists in the ocean so that's uh quite handy so yeah if you can offer some benefit to the shark that might be in your favor to befriend it for some reason when you were talking about fish cleaning their mouths my mind having talked about risk assessments went to I wonder what the fish's risk assessment for that was I think they're so small that it's like almost not worth it for the shark to eat them it's interesting that a species has
evolved to go into something an area we would consider dangerous which it sounds like it's not necessarily all that dangerous no also sharks have like very fun teeth so instead of like a set like you or I they have rows of teeth going back so like that is a lot of Maintenance you got to be doing on a mouth with all those rows of teeth a lot of fish to help clean off all the Dey yeah uh so I guess having said this is all about would you befriend a shark based on everything we've learned so far
about they can't really smell blood any better than any other fish and they don't know what it is anyway necessarily it's human blood um they're not too fusted about looking at you you don't NE need cage to swim with them they have other ways of sensing us Beyond sight and smell yeah and they make friends would you be friend of shark I consider myself already a friend of the sharks they might not know it I will always try and paint the sharks in a good light
because I do think they deserve it and I think they are really f fascinating from a zoology ecology point of view and there's so many of them you can't tar all sharks with the same brush I'm not saying that there are not incident in oh my goodness accidents involving sharks where people are unfortunately killed and you know lose limbs and that sort of thing but on the whole I think it's way blown out proportionate it needs to be people have accidents involving horses
and cows and all manner of things so I don't think we need to fear the Sharks I feel like you might be a little bit biased though you did say right at the start that you're already in advocation oh I'm completely completely biased I'm always a friend of the Sharks the animal I'm always on the side of the animals if we've learned nothing from my many podcast episodes I always pick them what about you Jasmine because you came in with some myths initially do you feel
like those myths are Justified and how sharks portrayed in the media is Justified I think like sharks really got the short end of the stick I think jaws and other myths around sharks really did a lot to damage their reputation I wouldn't be like racing to give a great white a hug I feel like it might not like that but I'll will admire a great white and other big sharks from a distance I would definitely try to hug like maybe a whale shark cuz they seem pretty cool whale sharks are incredible
I'd love to see a whale shark so I know nothing about them what's exciting about them they um couldn't really eat you if they tried because they are filter feeders like basking sharks ah so you would be better off trying to hug a whale shark I mean I wouldn't just cuz I didn't think they'd like it but you would be much safer in the first place they're also pretty massive aren't they they're huge yeah really really long where they get the name some of the uh longest fish in the ocean I think
potentially I wouldn't hug it but I would like to get really up close to it is a Greenland shark just because they look pretty funky Greenland sharks are also really cool now I can whip out even more shark facts because they're some of the longest living sharks so Greenland sharks can live to like 400 years old I think yeah which is incredible and also we've got to remember that sh s have evolved like 450 million years ago so if that doesn't mean anything to you there
were sharks on earth before Earth had trees and at that point Saturn didn't have any rings so you've got to admire their longevity and they've not evolved at all in that time all of these species have been around for that long oh no no no no they've evolved quite a lot unfortunately we don't have the Megalodon anymore I mean that would have been a shark I wouldn't have befriended to be perfectly honest cuz that was ridiculous so big yeah yeah yeah absolutely gigantic F sharks have
evolved over that quite long and distinct time period they must have had to adapt to quite a lot of changing things especially now with people doing so many things to the planet well it's funny that you mentioned people because we were on about how many uh sharks kill humans but think about how many humans kill sharks every year humans kill estimated 100 million sharks uh so this is like for both food but also accidentally so in some parts of the world shark fin soup is a delicacy the
other way that shark humans kill sharks is actually from fishing and by by catching so sharks getting trapped in Nets and then just suffocating cuz they can't move so yeah we kill a lot more sharks than sharks skill humans we're also ruining the ocean in terms of like you know sea level rise acidification pollution plastic even cocaine they found sharks very recently had ingested cocaine I I think probably from something like sometimes people ship cocaine on boats don't they and then the
boats sink and the cocaine ends up in the ocean and then it ends up in the sharks they think it's also water or waste runoff from like illegal Labs where they're making cocaine oh there you go now so is this like a widespread thing in a particular area it's not just they found like two sharks that had stumbled across this massive package of cocaine they found 13 13 Brazilian sharp-nosed sharks between 2021 and 2023 presumably if it's in the Sharks it could well be in other fish that more
people be eating yeah for sure could be in your food chain do you I don't know if like Shar cocaine Shar would be as good a movie as cocaine bear was I freaking loved cocaine bear that was pretty insane also based on a true story it's absolutely wild oh well there you go then I think having gone a bit off topic and started talking about films and cocaine not sharks probably leave it there probably a good idea yeah so we B some shark myths about how they smell blood and why
they probably want attack you and uh found some data to prove that many innocuous things are actually more dangerous like coconuts learned a bit about their evolution I feel like that could be another episode in itself I happily do an episode on Shark Evolution yeah there we go yeah and we've also found out about some really cute shark behavior where they make friends adorable so all of this leads us at least to conclude that despite what many films may try and tell us sharks just
aren't that scary I'd actually quite like to be friends with them I was going to say we never asked you what side you came down on yeah would you be friend shark I agree with you guys I think don't go and pest to them and do things they wouldn't like but yeah admire them from a distance I would be very happy if a shark came up to me in the sea and said hello and then swam off again could happen in England there are sharks in British Waters you might even see a
basking shark if you're lucky yes I'm always uh keeping an eye out so uh there you go so end our Sharky myth busting episode we will see you in next time the views expressed in this podcast belong in t to the person that said them they do not represent any industry or organization if you enjoyed listening to these views it would really help us out if you could rate US leave a review and tell a friend this podcast was sponsored by no one but if you're interested in
funding us to continue to have Frank discussions about science and engineering please get in touch [Music]