How do acquatic animals breath?

Answer 1

If they are a species of fish, they use their gills to get the oxygen out of the surrounding water. If they are aquatic mammals such as whales or dolphins, they breathe with lungs just as we do and have to get to the surface at regular intervals to breathe out and in.

Answer 2

Gas exchange in fish involves the gills.
The gills are on either side of a fish's mouth, and they're made up of a curved gill arch attached with a v-shaped double row of gill filaments. These gill filaments have on them little bumps called lamellae and it's in these that gas exchange takes place.
The Lamellae are very small, only a few cells wide and have a very thin surface for gases to diffuse through into the capillary network, so oxygen can be circulated around the body to cells. Since there are so many gill filaments and so many lamellae on them the surface area for gas exchange to take place is huge.

The disadvantages of gas exchange in fish is that gas exchange occurs underwater. Water has much less oxygen dissolved in it than air, and it has 50% more viscosity so it's more resistant to flow. Bony fish have overcome these problems by adaptions
1) Having a counter current circulation of blood in the lamellae, which means that the water that flows over the lamellae meets the most deoxygenated blood which is flowing in the opposite direction to the water. Oxygen in the water then diffuses into the deoxygenated blood through a concentration gradient. The water moves along the lamellae and loses more oxygen as it goes on. Carbon dioxide is also diffused out of the fish in this way. The deoxygenated blood starts off with plenty of carbon dioxide which it doesn't want, and travels along in the opposite direction to the water coming in. The carbon dioxide then diffuses out of the blood to the water which has a much lower CO2 concentration. Losing more CO2 as it goes on and gaining more O2 so in the end the blood is fully oxygenated. This gas exchange system is extremely efficient for the fish and enables it to extract 80% of the available O2 from water as opposed to humans who can only extract 25% from the air.
2)The water is continuously flowing over the gills in what's called a one-way flow, this means there's no dead space like in human lungs.

The other problem with gas exchange under water is that temperature affects the rate of oxygen diffusion greatly. A higher water temperature means less oxygen dissolved, and a lower temperature means more. So fish cannot survive very well in waters of high temperature. Also the gill filaments are supported by the buoyancy of the waters so that water can flow between them, but in air the gill filaments stick together.

Counter current flow only occurs in bony fish (eg goldfish, snapper) not in cartilaginous fish (sharks).

Answer 3

carbon dioxide and oxygen cycle- the exchange of these gases between living organisms and the environment.

Answer 4

well wow Ur here wasting Ur time for answers ask the teacher for help stupid

Answer 5

Depends on the aquatic animal. Whales have complex systems were jellyfish have no system for gas exchange.

Answer 6

Well they breathe through their gills

Answer 7

lungs