Do Fish Drink Water?
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Do Fish Drink Water?

August 15, 2019


All living things on Earth need water, because
the chemical reactions that make life possible happen in an aqueous solution. Which means us land animals have to drink
it to keep it inside of us all the time. But… what about fish? It seems like since they’re always in the
aqueous solution of whatever body of water they’re swimming around in, they wouldn’t
need to actually drink the stuff. But it turns out that some fish actually do
need to drink. And others do not. It depends on the fish, and what kind of neighborhood
it lives in. Water, you should know first of all, is really
into finding a balance. If you have a membrane that water can pass
through, and there are different concentrations of salt on each side, then the water will
always flow toward the saltier side of the membrane, until the concentrations on both
sides are the same. That means that freshwater fish have it easy. Since the concentration of salt in their bodies
is higher than the concentration in the water, that fresh water just flows right in, mainly
through their gills, and into their bloodstream. They also swallow some water when they eat
— I mean, it’s kind of unavoidable — but they don’t need to actively gulp down water. But, in order to retain that balance of concentrations,
the fish’s tissues still need to have some salt in them. And that’s where chloride cells come in. These are special cells in the gills that
produce large amounts of an enzyme that controls the flow of dissolved salts — like sodium
and potassium — across cell membranes. So, in freshwater fish, these chloride cells
work hard to bring just the right amount of salt into the fish’s bloodstream. Now, saltwater fish have the opposite problem. For most of them, the concentration of salt
in the water is higher than the concentration in their blood. That means that as they pass water over their
gills to breathe, the higher concentration of salt outside of their body is constantly
sucking water out of them. So these fish have to drink a lot, which they
just gulp down by the mouthful. But since the only water around is salty,
they have to filter out the salt to make it safe for them to absorb. A lot of that salt is filtered out in the
fish’s kidneys. But these fish have chloride cells in their
gills, too. It’s just that, in their case, those cells are constantly pumping salts out
of the bloodstream and into the saltier water. So they may be surrounded by water, but no
matter where they live, fish are always looking to find that balance. Thanks for asking. If you have a quick question
you’d like to ask us, we’re down in the comments below or on Facebook, Twitter, Tumblr, etc.
And if you want to keep getting smarter with us, you can go to YouTube.com/SciShow and
subscribe!

100 Comments

  • Reply mary sandifer January 28, 2018 at 11:55 pm

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  • Reply Brock Weaver January 29, 2018 at 5:03 am

    How do birds know which way is south?

  • Reply Ruptured Void January 30, 2018 at 1:15 am

    Is water wet

  • Reply The bloody Tears January 30, 2018 at 4:12 pm

    it is written in quran that every living thing is made up of water that was writen 1400 years ago. and much more science facts that are newly discovered and that is a real miracle

  • Reply systemdeadlock January 31, 2018 at 1:48 am

    good info thanks

  • Reply Derek February 4, 2018 at 9:40 am

    I mean they live in water

  • Reply m.Acordenero February 6, 2018 at 8:13 am

    Do mosquitos do?

  • Reply Dharrmentiran Harikrishnan February 8, 2018 at 4:51 pm

    Do a video about science in fishing 🎣

  • Reply Alex Pie February 9, 2018 at 11:38 pm

    Do fish drink water?do water drink fish? Do drink water fish?

  • Reply Pterafunk February 10, 2018 at 9:38 am

    Josh Wolf sent me

  • Reply The Burden February 11, 2018 at 4:34 am

    Could you "wean" a saltwater fish off of water?

  • Reply athana kop February 11, 2018 at 3:42 pm

    Do worms pee?

  • Reply 1337fraggzb00N February 11, 2018 at 10:36 pm

    00:18 "School of Fish" – the new movie with Jack Black.

  • Reply Justin Ruiz February 13, 2018 at 1:16 am

    Ironically, salt water fish can get dehydrated by drinking salt water that hasn't been filtered yet.

  • Reply Bastiavolpaine February 15, 2018 at 2:24 pm

    If a fish is insulted, do they feel a little salty?

  • Reply jcthagreat_4 February 16, 2018 at 11:49 am

    I never thought about this. Do alligator's drink water

  • Reply CON174th February 17, 2018 at 4:06 pm

    What happens to sperm if you don't have sex or masturbate? Does the body flushes it out or does it just sit in there? I know it's a weird question but I'm 34 years old and I have no idea and I love science. And before I even wrote this I try to find a video the answer is it so I don't have to ask. There was no videos.

  • Reply Mr. margad February 17, 2018 at 5:59 pm

    The real question is… does Fish pee?

  • Reply Big Booty Business February 17, 2018 at 6:47 pm

    If I car drove at the speed of light what would happen if you turned the headlights on

  • Reply Go Mikey February 17, 2018 at 11:36 pm

    0:27 is where the answer is

  • Reply Mc george Adelantar February 18, 2018 at 5:08 am

    I have a question
    Earth’s Gravity is greater than the Moon’s Gravity .. Why moon don’t fall on Earth ?

  • Reply Romans-ten9 February 19, 2018 at 6:16 am

    i lol when i read the title before clicking on the video

  • Reply Jeff gonzales February 20, 2018 at 11:16 am

    noob

  • Reply sanket kumar February 20, 2018 at 4:46 pm

    Can fish see things as clearly in water as humans do on land?

  • Reply Last Gaurdian February 20, 2018 at 9:16 pm

    Do humans eat air?

  • Reply - Vikiny February 21, 2018 at 3:35 am

    But is that water..

    WeT??

  • Reply Anarchist Maverick February 22, 2018 at 10:17 am

    Yes

  • Reply Tauhidur Rahman February 23, 2018 at 1:09 am

    why can we breathe with our nose and mouth but not with our Ears?

  • Reply XVikingX XDCX February 23, 2018 at 5:47 am

    This could possibly be the most video ever.

  • Reply The Vegan Troodon February 28, 2018 at 12:22 pm

    megalodon vs mosasaurus

  • Reply yung jose March 5, 2018 at 12:01 pm

    maybe they d r i n c c a i r

  • Reply Patrick De Ocampo March 6, 2018 at 2:18 am

    WHAT ARE THE DISADVANTAGES ABD ADVANTAGES OF GMO's or GENETICALLY MODIFIED ORGANISM??

  • Reply Emmillyy March 6, 2018 at 3:01 am

    is he john green

  • Reply Incognito * March 6, 2018 at 5:52 pm

    I'm kinda disappointed that no one retorted with, "Do we eat air?"

  • Reply Xavier Mendoza March 10, 2018 at 4:15 am

    Is this discount VSauce?

  • Reply RedFox109 March 11, 2018 at 1:37 am

    Thank you for talking fast so I dont need to watch for 10+ minutes.

  • Reply thatniggashrek savage March 12, 2018 at 3:30 am

    If we can’t see air could fish see water

  • Reply Jakub Kaczmarek March 17, 2018 at 4:42 pm

    Soooo LoL players can just take bath instead of drinking?

  • Reply I.A.P March 18, 2018 at 12:55 pm

    Salty fish

  • Reply the hamster guy March 19, 2018 at 1:43 am

    Do fish drink water ?

  • Reply the hamster guy March 19, 2018 at 1:43 am

    Guess what

    Chiken butt

  • Reply Vacant Heart March 19, 2018 at 5:20 pm

    The fact my dumb ass clicked this video

  • Reply Joe Mills March 22, 2018 at 3:02 am

    You would think that through this process of osmosis, Overwatch players would get water poisoning from swimming in the pool if humans had the same mechanic that fish do.

  • Reply Demolisher 275 March 22, 2018 at 9:13 pm

    Now we're asking the real questions

  • Reply xhris dorsey March 25, 2018 at 2:02 pm

    This is like Asking if humans eat air 😭😭

  • Reply Claudio Andrei March 30, 2018 at 3:30 am

    Tonight ill sleep early
    *me at 3am*

  • Reply Mood Killer April 18, 2018 at 12:51 am

    Don’t living thing need air to breath and how the hell does a fish get air

  • Reply Sandra Salerno April 29, 2018 at 8:19 pm

    Cool video!

  • Reply Amr Agiza May 9, 2018 at 7:58 am

    Why salt water fish can't live in fresh water and vice versa ?

  • Reply Hummer May 15, 2018 at 10:32 pm

    Here's the answer to that question simpler and faster
    https://youtu.be/pUpZDWXY9-8

  • Reply The Next Destination May 19, 2018 at 8:44 am

    https://youtu.be/KPXgc7unx_k

  • Reply Tamar ‘s Sketches May 19, 2018 at 3:53 pm

    Dis is how a fish drinks wota

  • Reply enrico lee May 27, 2018 at 3:32 am

    How about aquatic mamals?

  • Reply XDiamond GamerX June 9, 2018 at 10:22 pm

    Dis is hau a fish drings wota… laik dis

  • Reply Rotten June 10, 2018 at 12:21 pm

    https://youtu.be/EJDqVFCBvDU

  • Reply Hãlçyôn. poetry June 24, 2018 at 11:12 am

    https://youtu.be/poR5MlVDe-s
    Osmoregulation in amoeba
    Worth watching video

  • Reply Riot Zen June 24, 2018 at 1:04 pm

    Can fish see water

  • Reply Gabe Soule June 26, 2018 at 12:35 am

    So do freshwater fish pee or like what

  • Reply ꧁cutiepie꧂ June 27, 2018 at 2:59 am

    DES IS HOW A FEESH DRINKS WOTER
    BlEr BlEr bLaR

  • Reply Miles Lange June 28, 2018 at 1:31 am

    Dese is how a feesh drinks wata

  • Reply evelyn gichero July 4, 2018 at 5:11 pm

    I
    How do fish give birth

  • Reply Soul Raisin July 13, 2018 at 8:36 pm

    actually they drink like this
    https://www.youtube.com/watch?v=16A7wJpnnZU

  • Reply Star Gamz July 29, 2018 at 3:00 pm

    Dat is how a fish drinks wootar like dat

  • Reply artman40 August 5, 2018 at 7:22 pm

    But how do sturgeons handle the situation, considering that many of them spawn in freshwater but spend most of their days around estuaries and some even in open oceans?

  • Reply Sandra Dermark August 18, 2018 at 9:59 pm

    "Never thirsty" said Bilbo's fish riddle… Ever since, I have wondered…

  • Reply Cleidie Castro August 19, 2018 at 4:57 pm

    My dad told me when i was small they did there mouth thing because they were drinking

  • Reply Kelly Green August 20, 2018 at 7:00 am

    Is it true that animals that breed together yet have offspring that can't breed are of different species? I was told years ago that because horses and donkeys create mules that are unable to breed and this was proof they were different species.

  • Reply TerminalVerbosity August 21, 2018 at 9:53 pm

    Remember kids, stay in school.

  • Reply Asian 19 August 23, 2018 at 11:40 pm

    this is what i understand this is how a fish drinks water https://www.youtube.com/watch?v=pUpZDWXY9-8

  • Reply Mike Jakob August 24, 2018 at 7:48 am

    how do fish eat without drinking too much water? where does it go

  • Reply Nat248248 August 31, 2018 at 7:22 pm

    What about salmon? Aren't they fresh water and salt water fish?

  • Reply KGT UserCast September 3, 2018 at 8:04 am

    Saltwater fish are salty that freshwater fish dont lose salt just by drinking water.

  • Reply enxyy September 4, 2018 at 4:15 am

    Will camels don't really need it
    Bec they can leave without water

  • Reply Wagwan September 16, 2018 at 9:52 am

    Dis is haw a fish drinks water

    Lak this

  • Reply Zach Ryder October 8, 2018 at 1:30 pm

    2:03 As all things should be..

  • Reply Zoltan Ember October 10, 2018 at 9:53 pm

    Very interesting

  • Reply Reel Ahmed October 28, 2018 at 5:42 pm

    what is osmoregulation?

  • Reply Muhammad Arsalan November 4, 2018 at 3:05 pm

    hey john green why don't fish drown n the water im really curious pls answer this is epic yours sincerely sans undertale

  • Reply Joseph Koester November 8, 2018 at 2:20 am

    Needs salt.

  • Reply Fuzzy Turtles December 26, 2018 at 8:12 pm

    Dis is how a fish drinks wata

  • Reply T3ch the virus cat January 15, 2019 at 10:21 pm

    Dis is how a fish drink WOTER

  • Reply U.B.A.H February 2, 2019 at 4:59 am

    which one comes first in the evolution timeline, fresh water or seawater fish?

  • Reply Ducki es February 3, 2019 at 7:55 pm

    ThIs Is Ho A FiS DrInK wOtAh! LaK diS!

  • Reply Yang MouaVue March 1, 2019 at 4:58 pm

    Is a peanut a fruit

  • Reply Meme Time March 16, 2019 at 7:18 pm

    If we can’t see air can fish see water??

  • Reply Karthikeya Vallish March 17, 2019 at 4:12 pm

    why do

  • Reply Karthikeya Vallish March 17, 2019 at 4:12 pm

    Why do only some organisms exhibit metamorphosis

  • Reply Devrc B April 13, 2019 at 4:35 pm

    Please make atleast one overview video regarding the upcoming holistic view of systems biology towards life science..the "emergent properties"..gene ontology and stuff..please..please please

  • Reply Nomaan Nomaan April 19, 2019 at 7:25 am

    Dis is how the fees drink wata….. like dis

  • Reply h money April 22, 2019 at 3:37 am

    your the man

  • Reply Low Mein April 22, 2019 at 5:21 pm

    I’m only here because I’m high

  • Reply Đin ßagnes May 8, 2019 at 7:21 am

    DIS IS HOW FISH DRINK WUTAH LAK THIS

  • Reply tommy zoom May 25, 2019 at 6:24 pm

    Next tell them how fish CAN drown. Tired of people tryna catch me with these riddles

  • Reply Sandwich May 30, 2019 at 5:54 am

    so can I give a fish beer?

  • Reply Clownfish927 June 14, 2019 at 8:27 pm

    Yes. They do. This is how. https://youtu.be/EJDqVFCBvDU

  • Reply Khaliunaa Т June 16, 2019 at 3:23 am

    He is everywhere! Which channel am I supposed to follow in order to follow him??? Crashcourse? Scishow? or there is another channel too…

  • Reply Twitch June 18, 2019 at 5:38 pm

    Damn imagine being a salt water fish and having to drink like 24/7

  • Reply A B O V E D E A T H . July 18, 2019 at 5:32 pm

    Do fish get thirsty?

  • Reply Sinzarh August 3, 2019 at 9:32 am

    Dem bois thirsty.

  • Reply Caquiux August 9, 2019 at 5:19 am

    They drink air

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