Ryby jsou fascinující vodní tvorové, kteří obývají naši planetu už... Show more
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Updated Mar 31, 2026
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Ryby: Popis, Způsob Života a Zajímavosti
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Ryby - základní charakteristika a životní prostředí
Představ si, že bys musel celý život strávit pod vodou - přesně to dělají ryby! Tyto úžasné vodní živočichy žijí výhradně ve vodním prostředí a dokázaly se na něj dokonale přizpůsobit.
Nejdůležitější vlastností ryb je jejich dýchání pomocí žaber. Zatímco my potřebujeme kyslík ze vzduchu, ryby si dokáží vzít kyslík přímo z vody díky svým žábrám. Je to jako mít speciální filtr, který z vody vytáhne to, co ryba potřebuje k životu.
Ryby jsou ektotermní (studenokrevné), což znamená, že nemají vlastní "topení" jako my. Jejich tělesná teplota závisí na tom, jak studená nebo teplá je voda kolem nich.
Tip na zkoušku: Zapamatuj si, že ryby jsou nejstarší i nejpočetnější skupina obratlovců - tuhle informaci učitelé milují!
Potrava, pohyb a rozmnožování ryb
Stravování ryb je stejně pestré jako jejich druhy. Někteří jedí drobný plankton (takové malé "polévkové" organismy), jiní loví větší kořist nebo si pochutnávají na řasách a vodních rostlinách. Každý druh si našel svou specialitu!
Pohyb ryb funguje podobně jako u lodí. Ocasní ploutev je jejich "motor" pro pohyb vpřed, zatímco prsní a břišní ploutve slouží jako kormidla pro změnu směru. Některé odvážné druhy se dokonce naučily létat nebo šplhat - ryby prostě umí překvapit!
Většina ryb se rozmnožuje kladením vajíček, ale pak často své potomky nechají napospas osudu. Jen některé zodpovědné druhy hlídají svá vajíčka před predátory nebo dokonce rodí živá mláďata.
Zajímavost: Ryby existují na Zemi už více než 500 milionů let - to je mnohem déle než dinosauři!
Zajímavosti a fakta o rybách
Se svými více než 32 500 druhy jsou ryby skutečnými rekordmany mezi obratlovci. To znamená, že každý den by ses mohl učit o novém druhu ryby a stále by ti to trvalo skoro sto let!
Jejich ektotermní povaha jim dává velkou výhodu - nepotřebují tolik energie na udržování tělesné teploty jako my. Proto dokáží přežít i s menším množstvím potravy a přizpůsobit se různým teplotním podmínkám.
Fakt, že jsou nejstaršími obratlovci na planetě, znamená, že měly obrovské množství času na to, aby se přizpůsobily všem možným podmínkám. Proto je dnes najdeš v ledových vodách i v tropických mořích, v hlubokých oceánech i v mělkých potůčcích.
Pro lepší zapamatování: Ryby = voda + žábry + ploutve + vajíčka. Tuhle jednoduchou rovnici už nezapomeneš!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Ryby: Popis, Způsob Života a Zajímavosti
Ryby jsou fascinující vodní tvorové, kteří obývají naši planetu už víc než 500 milionů let! Jsou to nejstarší obratlovci na Zemi a zároveň jejich nejpočetnější skupina s úžasnými 32 500 různými druhy.
Ryby - základní charakteristika a životní prostředí
Představ si, že bys musel celý život strávit pod vodou - přesně to dělají ryby! Tyto úžasné vodní živočichy žijí výhradně ve vodním prostředí a dokázaly se na něj dokonale přizpůsobit.
Nejdůležitější vlastností ryb je jejich dýchání pomocí žaber. Zatímco my potřebujeme kyslík ze vzduchu, ryby si dokáží vzít kyslík přímo z vody díky svým žábrám. Je to jako mít speciální filtr, který z vody vytáhne to, co ryba potřebuje k životu.
Ryby jsou ektotermní (studenokrevné), což znamená, že nemají vlastní "topení" jako my. Jejich tělesná teplota závisí na tom, jak studená nebo teplá je voda kolem nich.
Tip na zkoušku: Zapamatuj si, že ryby jsou nejstarší i nejpočetnější skupina obratlovců - tuhle informaci učitelé milují!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Potrava, pohyb a rozmnožování ryb
Stravování ryb je stejně pestré jako jejich druhy. Někteří jedí drobný plankton (takové malé "polévkové" organismy), jiní loví větší kořist nebo si pochutnávají na řasách a vodních rostlinách. Každý druh si našel svou specialitu!
Pohyb ryb funguje podobně jako u lodí. Ocasní ploutev je jejich "motor" pro pohyb vpřed, zatímco prsní a břišní ploutve slouží jako kormidla pro změnu směru. Některé odvážné druhy se dokonce naučily létat nebo šplhat - ryby prostě umí překvapit!
Většina ryb se rozmnožuje kladením vajíček, ale pak často své potomky nechají napospas osudu. Jen některé zodpovědné druhy hlídají svá vajíčka před predátory nebo dokonce rodí živá mláďata.
Zajímavost: Ryby existují na Zemi už více než 500 milionů let - to je mnohem déle než dinosauři!
Sign up to see the contentIt's free!
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Zajímavosti a fakta o rybách
Se svými více než 32 500 druhy jsou ryby skutečnými rekordmany mezi obratlovci. To znamená, že každý den by ses mohl učit o novém druhu ryby a stále by ti to trvalo skoro sto let!
Jejich ektotermní povaha jim dává velkou výhodu - nepotřebují tolik energie na udržování tělesné teploty jako my. Proto dokáží přežít i s menším množstvím potravy a přizpůsobit se různým teplotním podmínkám.
Fakt, že jsou nejstaršími obratlovci na planetě, znamená, že měly obrovské množství času na to, aby se přizpůsobily všem možným podmínkám. Proto je dnes najdeš v ledových vodách i v tropických mořích, v hlubokých oceánech i v mělkých potůčcích.
Pro lepší zapamatování: Ryby = voda + žábry + ploutve + vajíčka. Tuhle jednoduchou rovnici už nezapomeneš!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user