Diatoms and Dinoflagellates / Fifth Dimension - Salami Rose Joe Louis

Gills usually consist of a thin filament tissue, lamellae

Tufted processes that have highly folded surfaces to increase surface area

The delicate nature of gills is possible because the surrounding water provides

support

The blood or other body fluid must be in it to make contact with the

respiratory surface for ease of diffusion

The high surface area is crucial to the gas exchange of aquatic organisms

Water only contains a small fraction of oxygen that air does

Water is 777 times more dense than air and is 100 times more viscous

Oxygen has a diffusion rate in air 10,000 times greater than in water

The density of water prevents the gills from collapsing and lying on top of

each other

Which is what happens when a fish is taken out of water

Usually water is moved across gills in one direction like

When a fish breathes, it draws a mouthful of water at regular intervals

Then it draws the sides of its throat together, forcing the water through the

gill openings

So that it passes over the gills to the outside

The gills of vertebrates typically develop in the walls of the pharynx,

Along a series of gill slits opening to the exterior

Most species employ a counter-current exchange system to enhance the diffusion

of substances in and out of the gill

With blood and water flowing in opposite directions to each other

The gills are composed of comb-like filaments, the gill lamellae,

which help increase their surface area for oxygen exchange