How Fish Eat (in SLOW MOTION!) – Smarter Every Day 118

How Fish Eat (in SLOW MOTION!) –  Smarter Every Day 118

Hey it’s me Destin, welcome back to Smarter Every Day. So as dads, when you go fishing you spend a lot of time thinking about how to get the fish to bite, but you don’t really think about how mechanically the fish do the bite. Does that make any sense? So today on Smarter Every Day we’re gonna go to James Cook University in Australia, and look at how a fish bite takes place in slow motion using a Phantom camera. You’re getting Smarter Every Day. [ music ] OK, so, how do fish eat. So they suck food in, but they have to generate that flow right? – Oh you talking to me? – Yes I am, Dr Seymour. – I’m trying to do two things at once here. – Alright so we’ve got a big tank of.. barramundi? Am I saying that right Richard? – Mm hmm. – Why do you have a stick and a string here? – OK this is the stick of death. This is what we use to feed everything with. So if we hold that over the tank on the water, then you’ll be able to focus on that, and you’ll be able to see the barramundi come up and [sucking sound]. – OK, got it. – Here he comes, gone! [ music ] (Destin) So how do they actually create that flow inwards? Are they, like increasing the chest cavity somehow? – It’s the buccal cavity or the mouth. – Say what? – The buccal cavity, the mouth. So they’ll open their operculum, which are the gill flaps, and they open their mouth wide, and that sucks the water in, so they’re basically producing a vacuum in behind it. – Buccal cavity. – Yep. – When they open their mouth, why does flow not come in the gills? – Because they open the front first. So you’ll have a look, and you’ll see it on the high speed, they’ll open here, and then that’ll go. And they’ll push.. all the water then comes out through the back of the gills. When you see it on the high speed it will make sense. – So that’s how they.. No way. – Yeah yeah! – OK I just had that moment where I figured it out. – Dong! – Yeah, so the fish opens his mouth, and he starts flow in, so you have fluid momentum going in, and then he still has momentum going in, and if he doesn’t get rid of that somehow it’ll push him backwards. – Yep. – So when it goes in, after he gets it in his mouth, then he opens his gills and he releases that momentum. – Yes. – Shut up! I’ve been fishing my whole life and I didn’t know that. – And you’ll see it on the high speed. – Really? – Yeah yeah. [ music ] – Alright. Dude that’s awesome! – Do it out here in the light. Woah! – So the fish is coming up to the food, and instead of accelerating the whole body to grab the food, fish have a very complex mouth, where they can throw the jaws forward. So instead of throwing the whole body mass forward, at the last moment you have this very complex mouth with all these bones that just opens up, so it closes that gap with the prey a lot quicker and a lot easier. (Destin) OK so he doesn’t have to accelerate the mass of his whole body, just the front jaws. – No just the jaws, and so when the jaws are thrown forward as Jamie explained, it’s creating this huge volume and the water has to rush into it. And then out through the gills. And so you’ve got this suction feeding. – That’s awesome. – Suction feeders, ram feeders you can call them. – That’s awesome, really. – That’s good. – Do all fish do this? – No. Only a few fish actually suck their prey in. Because these guys don’t have teeth as such. – OK, so teach me the terminology. So there’s the buccal cavity.. – Which is the mouth, yep. – They open the buccal cavity and then they open the gills.. – Or it’s the opercular flap, so the gill is behind this flap. So when that’s closed off, the only entrance is in through the mouth. Water sucks in, then you’ve gotta get rid of it somewhere, so you then open that out and it’ll all blow through the back here. – Because you have to dissipate momentum. – OK, James Cook University just taught me something about how fish eat, and I’m assuming you.. – Does this work on like your goldfish in your aquarium? – Yeah, same sort of thing. – When you put the flakes in, you’re gonna see him open his mouth and then open the operculum.. – Mm hmm. – And dissipate that over the pectoral fin. Yeah. You’re getting Smarter Every Day. I’m Destin, have a good one. Have you caught anything yet? – No sir. – Do you enjoy it anyway? – Yes sir. – Do you wish we had an audio book to listen to? – Yes sir. – Which one? – Captain Nemo. – Pull, pull! Pull son! Pull it! – I got a fish! – There you go! – Keep reeling it in! – Alright, OK. -It still has a worm in his mouth. He Does! Let’s let him eat that worm. (Destin) So this is what happens. He opens his mouth right here, the water gets pulled into his mouth and then he opens his gills after that and he shoots the water out of that. Does that make sense? – Yes sir. – Hold on tight, don’t be scared. You ready? Now slowly let him back in the water. There you go. Alright, so that’s how fish eat. If you are interested in supporting more fishing trips and more episodes of Smarter Every Day, you can support us by going to and getting a free audio book. Does that sound good to you? – Yes sir. – What audio book do you recommend? – Umm.. 20,000 Leagues Under the Sea. – That’s right. Where do we listen to that? – In the car. – That’s right. So if you’re interested in helping Smarter Every Day, go to, download a free audio book, you can get 20,000 Leagues Under the Sea, and you can help Smarter Every Day, it’d be a real good thing. Anyway, thank you very much. You want to say thank you? – Thank you! – Anyway I’m Destin.. – And bye! – And bye. I’m Destin, you’re getting Smarter Every Day, have a good one.

100 thoughts on “How Fish Eat (in SLOW MOTION!) – Smarter Every Day 118

  1. I think that out of all of your friends and guests, Dr. Seymour is my favorite. I love his passion (and yours of course), I like his accent, and I also have an interest in marine biology, so there's that.

  2. Even Asians don't call their father "sir" even if they are very scared of their father. I guess it's a western thing.

  3. this is how my betta fish eat, my clownfish are different. They actually have an articulating jaw like ours so it just opens/closes. they more much. And my tangs kinda rub their teeth against the rock to eat.

  4. One thing that wasn't mentioned is the reason why they eat like this versus going straight into their pray. They have to create a vacuum effect to suck the fish in, otherwise the momentum of their body going straight through their target would create a current pushing their prey away right as they get close. Super interesting stuff but pretty logical explanations. Love it!

  5. Whats with the yes sir, no sir stuff? I don't know of any kids that call their dad sir unless forced to by a strict military style father.

  6. Whats with the yes sir, no sir stuff? I don't know of any kids that call their dad sir unless forced to by a strict military style father.

  7. So they actually use the momentum of the displacement of water from the surface into their mouth cavity to suck the fish in and then shoot it out their gills. That is cool and very efficient! I always wondered when fishing how an entire barber vanished momentarily with just simple fish bite. LOL

  8. Schools should start using smarter everyday as a tool to teach people! Not only on how this amazing world works but how to grow up and be a great person! If more people were like destin the world would be a much better place!

  9. You're the man! I was thinking on watching a largemouth bass on a high speed camera and I came back to your show! It would be amazing if you can do that with a largemouth. Their mouth seem to be way much bigger that he fish here. I think it would be even more spectacular! Thank you!!!

  10. I really love how you spend time with your children in episodes like this. It's quite heart warming, and you're a father role model for me!

  11. Dr. Seymour is SO grounded. Here's a renowned Scientist with not only a post grad degree but a True accomplished Doctorate (Hence why he's a DOCTOR 😉 ) — And he acts like a Rugby player at the pub.. only he has this genuine curiosity and vast knowledge from his intriguing brain.. causing him to be likably intelligent in a position of authority. What a professor he must be.

  12. its so bad to see comments about "yes sir" even after he made that writing i guess a lot of years ago, people still dont read it

  13. You get that feeling of “whuuuuuuut? Are you serious?” When you learn these things. And the slow capture is everything!!!!!!! I am really learning something new everyday. I love it!!

  14. Today, I am more impressed with your children's upbringing than the science! They have learned respect and courtesy at this young age. Kudos to u and ur madamme!

  15. ✈⛺More OZ tour SEEN 1ST 2013 then one in 2015 now this one july 2014 Dam you guys travel here alot👍 💃- – 🛬

  16. Please do another fish slow mo get tail and fin mechanism thats the real wonder the muscle to fin minor adjustments like wings underwater. Thanks for the videos they helped so much in so many random experiment ive done i can go to get solid base lines to compair for some things thank you

  17. So creepy hearing your kids say sir after every question you ask them. Yes sir, no sir, yes sir. Talkin like they're in trouble with the principal or a step dad instead of their own dad. Hope they're out of that phase now that they're older.

  18. the momentum of the flow makes sense but how does it separate the solids to liquid? like if they are eating the prey they suck it how come prey doesn't get expelled from the gills as well? is there some sort of net on the gills that prevent solids from passing through?

  19. How the fish gets the prey item in the mouth is not at all as interesting as how it gets from the mouth back into its stomach and past the gullet

  20. Ah men, this sucks I thought I was going to see inside the fish with that phantom but it’s just the mouth

  21. i guess Seymour found a new Job after his last one…ended in a horrible disaster…glad Zarnakand is in peace for now…way to go seymour!

    p.s. i liked you more with pourple hair and the tattoos but i guess the Job required a normal looking Guado…

  22. 2 things. 1) I love this video, I do a lot of fishing, nice bluegill btw. And 2) your son will grow up to be a very good man with a father like you! Thanks for making me smarter every day!

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