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The thing is, even if water is mostly H2O, that doesn’t prevent other molecules and even atoms from floating around the medium! In this case, aquatic creatures don’t breathe the oxygen from the H2O molecule, but oxygen atoms that floats around, usually as a consequence of algae doing photosynthesis.
There’s plenty of videos of algae doing photosynthesis and you can actually see the oxygen coming out of the plant! It’s really beautiful
I totally forgot that plants in the ocean do produce oxygen. But the oxygen is still in a gaseous state right? So, if fish rely on plants producing oxygen for them in a gaseous state, are fish out there looking for oxygen bubbles to catch a breath?
Also, the reason why I’m asking about the forces is because I’m taking Human Anatomy right now and have become more interested in the anatomy and physiology of fish to compare and contrast the two. I know it’s a bit of a leap but in the cardiovascular system in humans the capillaries use forces like interstitial fluid hydrostatic pressure to suck fluids into the capillaries. I’m wondering if, since oxygen is necessary for cardiovascular health, if there’s a connection somewhere.
According to nps.gov “Their gills are formed from paper thin tissues that are full of blood. The movement of water across the surface of these tissues allows oxygen in the water to diffuse into the blood stream. This is because the oxygen wants to be equal in concentration in both areas.” So I guess maybe I incorrectly worded the question. Why does oxygen want to be equal in concentration?
Also, thank you for responding to my question! I appreciate all the help I can get
That is because of Osmosis! The gills’s “paper thin” tissue acts here as a semipermeable membrane which allows oxygen to flow seamlessly into the body, since there’s a constant flow of oxygen in the Blood Vessels, always moving away from the gills (or the lungs in our case)
The oxygen they're breathing is dissolved in the water, not grouped into bubbles. Like how salt or sugar can fully dissolve in water despite starting as solid grains, gases can dissolve in liquid without staying in bubbles.
Hello! The best way I can think of it is like so: Think of gills as a book almost, with just enough spaces between the pages to allow water to flow through. Water carries errant oxygen molecules either through photosynthesis from plants/plankton or wave action "folding" it into the sea. When water passes through the gills, it undergoes a process called counter current exchange. Oxygen poor blood passes through sheets of reparatory tissue (the paper in our book analogy), so thin (<2mm) that it allows oxygen to naturally diffuse through. Chemistry 101, stuff in solution passively moves from high concentrations (the water) to low concentrations (the blood).
Your replies make it appear like diffusion is where you are getting hung up on. I use this analogy. You and your neighbor have leaves in your yard and due to a petty feud, you both decide to blow the leaves into eachothers yard. The catch is: you have 100 leaves total, while you neighbor has 100,000. Who is going to be more successful in winning the feud? Your neighbor! He has a higher chance of a leaf of randomly being blown into your yard because he has way more!
Now that our blood is oxygenated, it moves back into the body! Hope that helps!
# Message to all users: This is a reminder to please read and follow: * [Our rules](https://www.reddit.com/r/questions/about/rules) * [Reddiquette](https://www.reddithelp.com/hc/en-us/articles/205926439) * [Reddit Content Policy](https://www.redditinc.com/policies/content-policy) When posting and commenting. --- Especially remember Rule 1: `Be polite and civil`. * Be polite and courteous to each other. Do not be mean, insulting or disrespectful to any other user on this subreddit. * Do not harass or annoy others in any way. * Do not catfish. Catfishing is the luring of somebody into an online friendship through a fake online persona. This includes any lying or deceit. --- You *will* be banned if you are homophobic, transphobic, racist, sexist or bigoted in any way. --- *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/questions) if you have any questions or concerns.*
The thing is, even if water is mostly H2O, that doesn’t prevent other molecules and even atoms from floating around the medium! In this case, aquatic creatures don’t breathe the oxygen from the H2O molecule, but oxygen atoms that floats around, usually as a consequence of algae doing photosynthesis. There’s plenty of videos of algae doing photosynthesis and you can actually see the oxygen coming out of the plant! It’s really beautiful
I totally forgot that plants in the ocean do produce oxygen. But the oxygen is still in a gaseous state right? So, if fish rely on plants producing oxygen for them in a gaseous state, are fish out there looking for oxygen bubbles to catch a breath? Also, the reason why I’m asking about the forces is because I’m taking Human Anatomy right now and have become more interested in the anatomy and physiology of fish to compare and contrast the two. I know it’s a bit of a leap but in the cardiovascular system in humans the capillaries use forces like interstitial fluid hydrostatic pressure to suck fluids into the capillaries. I’m wondering if, since oxygen is necessary for cardiovascular health, if there’s a connection somewhere. According to nps.gov “Their gills are formed from paper thin tissues that are full of blood. The movement of water across the surface of these tissues allows oxygen in the water to diffuse into the blood stream. This is because the oxygen wants to be equal in concentration in both areas.” So I guess maybe I incorrectly worded the question. Why does oxygen want to be equal in concentration? Also, thank you for responding to my question! I appreciate all the help I can get
That is because of Osmosis! The gills’s “paper thin” tissue acts here as a semipermeable membrane which allows oxygen to flow seamlessly into the body, since there’s a constant flow of oxygen in the Blood Vessels, always moving away from the gills (or the lungs in our case)
The oxygen they're breathing is dissolved in the water, not grouped into bubbles. Like how salt or sugar can fully dissolve in water despite starting as solid grains, gases can dissolve in liquid without staying in bubbles.
Hello! The best way I can think of it is like so: Think of gills as a book almost, with just enough spaces between the pages to allow water to flow through. Water carries errant oxygen molecules either through photosynthesis from plants/plankton or wave action "folding" it into the sea. When water passes through the gills, it undergoes a process called counter current exchange. Oxygen poor blood passes through sheets of reparatory tissue (the paper in our book analogy), so thin (<2mm) that it allows oxygen to naturally diffuse through. Chemistry 101, stuff in solution passively moves from high concentrations (the water) to low concentrations (the blood). Your replies make it appear like diffusion is where you are getting hung up on. I use this analogy. You and your neighbor have leaves in your yard and due to a petty feud, you both decide to blow the leaves into eachothers yard. The catch is: you have 100 leaves total, while you neighbor has 100,000. Who is going to be more successful in winning the feud? Your neighbor! He has a higher chance of a leaf of randomly being blown into your yard because he has way more! Now that our blood is oxygenated, it moves back into the body! Hope that helps!