Can sharks smell blood from miles away?

With their acute sense of smell, sharks can detect minute quantities of blood from miles away. Does this mean that female swimmers who are menstruating should be wary or avoid swimming? Tune in to this podcast from HowStuffWorks.com to find out.

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve Camray.
It's ready. Are you welcome to Stop Mom never told you?
From house Stop works dot Com. Hello, and welcome to
the podcast. This is Kristen and this is Molly. Molly.

(00:21):
As you well know, Shark Week of Discovery Channel, in
which everything shark takes over the air waves. Tracy Jordan's
favorite week, Tracy Jordan's favorite week. Yes, for fans of
thirty Rock, which we probably shouldn't plug because it's on
a different network from Discovery Channel, but still, Shark Week
is coming up. So we're gonna talk about sharks today.

(00:44):
And Molly, how how on earth can we talk about
sharks relationship to women? It seems pretty disconnected, right, No,
I see a very obvious connection. Oh well, I do,
do explain. Well, the thing I always think about sharks.
I think it's a big urban myth sits out there,
is that sharks cansmell blood from miles away, and obviously,
without getting too crude about it, this is a particular

(01:05):
importance to women because there's a particular time of the
month in which we release between fifty millions of blood
and I think I've heard about that. It's called menstruation,
all right, Molly. So yeah, the question that the big
question is should should we really avoid swimming the ocean
if we are on our periods because we're basically shark magnets.

(01:29):
Let's talk about it, okay, Let's talk about sharks incredible
sense of smell, because the fact of the matter is
sharks can't smell blood from a very long distance away
because they have some pretty incredible nasal anatomy, right, Molly. Yeah.
Sharks are sometimes known as swimming noses because they just
can smell so well. Imagine being uh, in like this
vat of like ten million things, okay, and there's only

(01:52):
one part of those Temblian things that's like fish extracts.
You put the shark in there at the ten billion things,
it can smell the fish well, and out of ten
billion things it will smell. That's incredible. And like, let's
say you're get in a swimming pool, Christen, and then
we put a teaspoon of vanilla or cinnamon or something
smelling in there. Would you be able to smell it?

(02:12):
Probably not? Probably not. It can't smell underwater, obviously, Well,
sharks can, and they could smell something just that tiny
a teaspoon, So yes, something that's as far away like
let's say you get this huge gaping cut in the ocean,
you step on a shell or something, God, and there's blood. Yes,
the shark will smell that, all right. Well, the the
cool thing to me, I thought, the cool thing about

(02:32):
shark noses was that they have one nasal opening just
dedicated to bringing water and they actually suck the water
into their nose and the other side of the nose
is dedicated just flushing that water out. And the reason
they can sense that what was it, the one billion
particle in the water is because they have these nasal

(02:52):
sacks that are filled with sensory cells that will analyze
all of the different different cells in the in the
water that they sniff up and then release it back.
And then their brain is able to track down the
specific um pheromones and of potential mates or sense of
their prey um, so they can know exactly when um,

(03:14):
they've sniffed up some some blood and need to go
on the attack. Yeah. And actually, you know you were
talking about these sensory cells. Two thirds of the shark's
brain is dedicated to that sort of machinery that helps
them figure out what am I smelling? Is they prey
isn't a mate, and so they basically have smell on
their mind all the time. Yeah, so now we know
that sharks have incredible senses of smell, are they more

(03:37):
finely tuned to blood? And I hate to be gross,
but two period blood to menstrual blood menstrual blood. So
there's really no way to study this Christian that's going
to be sort of you know, the cop out answers.
And until we put a bunch of menstruating women into
an ocean and a bunch of non menstruating women to
the ocean at the same time and see if, like

(03:58):
one of the groups is more prone to get attacked
by shark, there's no way to answer the question. I'd
be hard to find participants for that study exactly that
I signed up for that one. That's the problem is
it will never probably be definitively proved well according to
you George H. Burgess, of who manages the International Shark
Attack Files. He says that any bodily fluid is attractive
to sharks, but this also includes urine. So if you

(04:22):
are using the bathroom in the giant toilet that is
the ocean. Uh, that could be attracting sharks in addition
to blood. But he also thinks that blood is probably
the most attractive organic fluid. But some other researchers, notably
a guy named Carl Edmonds who is no relation to me,
theorizes that while sharks can you smell the blood, and

(04:44):
they're attracted to some blood, probably like a blood from
a cut, menstrual blood might be a little different. It
might be sort of considered a dead organic blood, and
thus it actually repel sharks. But again, like I said,
until I've got some sort of study where women are
going to get in the ocean and swim around, it's
really not going to be We're not able to tell
if sharks are repelled by it or not. Yeah. Uh, Well,

(05:05):
the good news is that statistics are on women's side.
The good news the good news the female listeners. Right.
The good news for female listeners is that we are
way less likely to be attacked by a shark than
a man. And that's basically because men are just more
often engaged in riskier behaviors in the water, such as

(05:27):
swimming farther out or going deep sea diving. Or doing
spear fishing and things like that. For instance, according to
the International Shark Attack Files from to two thousand eight,
of divers who were the victims of unprovoked shark attacks
or men and only or women, And that number is

(05:49):
starting to even out a little bit more as more
women um are doing scuba diving, but still men men
are the ones getting getting bitten. But even those they
get it, that's pretty rares. And I don't have some
statistics about how rare it is to be attacked. Well,
not only is it rare to be attacked by a shark,
it's even more rare to be attacked and die from

(06:11):
a shark. According once again to the International Shark Attack
Files from nineteen fifty nine to two thousand seven, nearly
two thousand people have died from being struck by lightning,
but only twenty three have died from shark attack. I
like my adds. Yeah, I mean, you're You're way more

(06:32):
likely to die by being struck by lightning than dying
from shark attacks. People and say it like that because
I'm a fear of being struck by lightning. But well,
I think, well, that's another podcast topic to talk about.
But back to sharks and blood. I think the other thing,
you know, we mentioned fifty mil leads to a hundred
fifty mile leaders of blood. That's an entire period. So like,

(06:52):
let's say you're going diving for a few hours, You're
not going to be releasing that much, right, But I
think the safest thing we can say is where a tampon? Right?
And this is the same, uh, the same advice that
goes for women who are out in the wild camping
or camping, right, because the same kind of urban myth
about sharks being attracted to menstrual blood has been extended

(07:14):
to grizzly bears also being attracted to menstrual blood. Like,
if you're on your period, don't go camping because bear
is gonna hunt you down and eat you. But we
found this article in Backpacker magazine that basically says that
if you are on your period and you're wearing a
tampon and you are being sure to dispose of them

(07:34):
properly and far away from the tent area, you should
be just fine. Yeah. And what was most interesting to
me about this article was it explained where this myth
comes from in terms of bears. And I'm sure it's
probably something similar with sharks. But basically, back in the sixties, uh,
some women were killed by bears in Glacier National Park

(07:55):
and a staffer said, oh, they're probably on their period,
and that was the sound bite that got pad depth
and repeated by all the news sources. And we don't
really know where the shark blood thing came from, but
I wouldn't be surprised if it star of the same thing.
And in researching all of this, we did find that
there are a few potential risks if you're going diving
deep sea diving if you are on your period. Yeah,

(08:17):
this is not uh strictly proven by science yet, but
basically some researchers have done work that suggests that at
certain points uh in your menstrual cycle, particularly if you're
on oral contraceptive pills, you might be more susceptible to
decompression illness a k a. The bends. But you know,
I don't think this is any reason to necessarily set

(08:38):
out a deep sea diving trip if you feel okay. Obviously,
if you're feeling damn, I feeling gross, which can happen,
you know, maybe be a little more careful, don't go
as deep don't go as long, etcetera. You know, play easy.
But you know, when we were researching this, we saw
a lot of articles that were like, women who are
on their periods can't go something because of sharks. And
I think we need to stop blaming the sharks for

(09:00):
not getting out there and getting in the water. Yeah,
it's just fine if you get out there, get in
the water. And the one thing that I try to
remember when I go to the beach Molley is that
sharks are most active at night, and so if you
go swimming between general office hours between nine am and
five pm, you should be safer in general and just
be smart in the water. You don't have to worry

(09:21):
about your period somehow attracting them. It's gonna be more
your activity, like things like wearing um shiny reflective jewelry
while you're swimming will attract them. Um actual open wounds.
Like you said, if you step on a shellfish or
or a shell and your foot starts bleeding, that's that

(09:42):
might be more of a problem, but it's more just
common sense things of staying safe and in the water
will keep you safe from sharks and also remember far
more likely to be killed by lightning. Sorry, Molly, to
play on your phobia, but but that's okay. I will
I will settle for being one of those sort of
like commercial shows that tells women not to let that
time at the months slow them down, which I think

(10:03):
is what we've done today. That's right, ladies, just put
on those swimsuits and go for it. Speaking going for it.
If you are gung ho for sharks and want to
go for some more shark info, man, oh man, is
there a lot of it out there. Of course, We've
got shark week dot com, Frenzied waters dot com. And
after you've had your fill of online information, it's time

(10:23):
to watch the television. Oh yeah, Shark Week is happening
on Discovery Channel from August two through eight. And uh,
probably after you watch all that, if you're not are
not terrified of sharks, you probably will be. So listen
to this podcast again so you can get rebbed up
to go back to the beach one last time before

(10:44):
the summer sun fades. Well that was kind of a downer,
so let's end on an up note with the listener mails. Okay, um,
today I wanted to read email we got from Katie.
She wrote in response to our podcast about whether men
or women are happier. And you know, during that we
were talking a lot about the role of career might

(11:06):
play in terms of a woman's happiness, and she gave
us a good perspective. I think that you know neither
Christen nor I have right now, which is that of
a stay at home mom. So this is what uh
Katie wrote. As you discussed why women may or may
not be happier. You spoke with the assumption that a
woman has to have a career outside the home to
be to feel fulfilled or be happy. This and this

(11:27):
is an assumption that everyone makes, but I feel it
is very wrong. I will I'm a woman with a
college education and who is perfectly capable of having a
great career, but who has chosen to stay at home
because I feel very strongly that the most important thing
I will do is raise my children. On one hand,
being a stay at home mom is very challenging, so
I can understand how people see it as incapable of
making someone happy. Is a seven job. Rewards or acknowledgements

(11:49):
are few and far between. No one is ever going
to promote you or give you a raise. It is
often monotonous and alienating and so on and on. However,
with great sacrifice comes great rewards. Raising children is very
fulfilling as you it to see your child and discover
the world and become their own people. Study after study
also states that nothing affects how people turn out more
than their parents. So I feel that things I do
with my children will have long and lasting effects into

(12:11):
the future. It is a job where you can really
focus on altruism and relationships and all the things that
studies say and make you happy. Very interesting. Thank you
so much for writing in Katie, uh and Molly. I
have a letter here from Cindy, who was writing in
response to our episode on chick Lit. She said, Hey,
Molly and Kristen. In your latest podcast, you mentioned that

(12:32):
your female readers didn't read many chick lit titles. I
just like to point out that the sample may not
be very representative of the population at large. While Steffman
never told you was targeted largely at a female listeners,
I did not find it until I listened to other
house stuff Works podcasts and suspect others had similar experiences.
The website itself, meaning how stuff Works dot Com may

(12:54):
not be attracting all the same readers as say Nora
Robert's novels. It's like how Cosmos Sir Bays would show
women to be more sexually active than those surveys done
by public health organizations. Just my two cents. Love your
podcasts and keep up the great work. Thanks for the
two cents, Cyndy. I think that's a that's an interesting
point she made. It's an interesting point. I could see

(13:14):
how that could happen. But I think all our listeners
can help broaden our base by telling all their friends
about stuff. Mamember told you shame. Let's plug and keep
sending us your reading list because we are going to
keep reading them on each episode. Yes, I think we
have one for today. Indeed we do, Molly Um. This
is from Shannon and Shannon first of all, had a

(13:39):
very interesting tid but that a few of you guys
have sent in about J. K Rowling. She said that
the publishers were concerned that boys wouldn't read a book
written by a woman, and so they encouraged uh J.
K Rowling to actually go by that that pseudonym and
use her initials to use her initials uh. Shannon also
just finished reading the Poison Wood Bible by Barbara Kings Salver,

(14:02):
and it is a heavy read, so she is now
reading what she calls a trashy little of paperback, which
is a good strategy. Usually, if I've got to read
something heavy, I balance it out with something light, something
kind of easy. Sounds good. Well, folks, if you would
like to get in touch with me and Molly, please
send us an email at Mom's Stuff at how stuff
works dot com. And you can always check out our

(14:25):
blog how to stuff at how stuff works dot com.
And finally, for more information on virtually any and everything,
why don't you just said on over once again to
how stuff works dot com for more on this and
thousands of other topics. Does it? How stuff works dot

(14:45):
com brought to you by the reinvented two thousand twelve Camray.
It's ready, are you