Just like all other animals, fish need oxygen to survive. Diana - Well I think they work a little bit like really efficient lungs. To do this they use an arrangement of filaments on either side of their neck called gills. If the skin on the gills is thin, this also helps. How long does it take a fish to recover? Fish breathe through gills instead of lungs. share. Most fish have four gills on both sides of their head. The air we breath is 20 percent oxygen, or 200,000 parts per million.” Water holds 4 to 8 parts per million of oxygen, he adds. “It’s a big challenge for a fish. Because they live in water, they have evolved gills which enable them to remove dissolved oxygen from water. 6 comments. I decided take it a step further and run a study to answer these questions. So, when a fish opens its mouth, in goes the water, it goes into the gill, and they've got a really thin membrane over which the water flows, and on the other side of membrane, blood is flowing and it's flowing in the opposite direction which means that any oxygen which is dissolved in the water can then In his classic 1966 paper, `The dimensions of fish gills in relation to their function' (Hughes, 1966), Hughes founded the modern age of gill biophysics, by measuring various gill tissue dimensions in fish ranging from 12 g mackerel (Trachurus trachurus) to 1.5 kg angler fish (Lophius piscatorius), to analyse gill resistance to water flow. In order to breathe underwater, fish have to extract dissolved oxygen from the water. Surface area is always the answer to most science problems! They are packed with blood vessels, ready to absorb oxygen. A freshwater fish will constantly lose salt through its gills, while a salt-water fish may have to spend a lot of energy keeping excess salt out. Finally, does pouring soda on a fish’s bleeding gills actually work? They work basically the same way. It just takes a lot of energy.” These body parts work like a pump to keep water moving over the gas absorption surfaces of the gills. “It takes an awful lot of work for the fish to exchange gases, particularly oxygen. Gills are highly folded, giving them a large surface area and maximising the efficiency of gas exchange. ELI5: How do fish gills work? Fish have internal gills and some newts and first stage frogs have external gills. Water enters the fish's mouth and then the fish forces water across its gills, past many tiny blood vessels, and out the gill slits. Fish gulp in oxygenated water and force it through their gills and then out through the gill openings while also continually pumping deoxygenated blood from the body into the gill fi laments. Most fish possess gills on either side of their head. Water flows past the gills and the tiny bit of dissolved oxygen in the water is absorbed while carbon dioxide is released. Gills are branching organs located on the side of fish heads that have many, many small blood vessels called capillaries. they will be able to absorb oxygen. It just takes a lot of energy.” Gill filaments. Inside the fish’s gills, feathery filaments hang like curtains. For a freshwater fish, the challenge is to prevent the loss of salt from its body. Gills are tissues made up of feathery structures called gill filaments that provide a large surface area for gas exchange. But gills have a much harder job than lungs, Malison says. Fish use specialised surfaces called gills to carry out gas exchange. First and foremost, they wanted to know the best practices to help a bleeding fish after being hooked in the gill. When a fish gulps in water, the gill flaps close to stop water from spilling out. When water passes through the gills, the dissolved oxygen diffuses into the bloodstream. I know they filter out oxygen and all that, but I'm really interested in knowing how exactly they do it. While mammals' lungs work with air, which is 200,000 parts per million oxygen, a fish's gills are working with water, which is only up to 8 parts per million oxygen.