How do gills work, and could i have a website with a diagram of gills?

Answer 1

Fish extract oxygen from the water using their gills in a manner somewhat similar to how land animals extract oxygen from the air using lungs. In both cases, oxygen diffuses into the blood through a thin, permeable membrane. Basically, the lungs of mammals are like a balloon with a single opening. Air goes in, and then goes out again through the same opening (bi-directional). Oxygen is transferred from the air to the blood across a thin membrane in the lungs, in the tiny, surface area enhancing pockets called alveoli . Gills, on the other had, can have water flowing past them constantly in one direction (unidirectional). ). Most fish take advantage of this by having a "counter current" blood system where the blood in the gills travels in the opposite direction to the water flow. This allows for up to up to 80% efficiency in getting the oxygen from the water to the blood, much better than what lungs can accomplish. This efficiency is also helped by the very fine structure of the gills, which greatly increases their surface area. Fish have very these very efficient gills because of the fact that water contains about one-thirtieth as much oxygen per volume as the atmosphere above it. To put that in perspective, if we were somehow able to "breathe" water, we would need to take about 450 "breaths" per minute just to get enough oxygen into our lungs!

http://www.kwic.com/~pagodavista/schoolhouse/species/fish/fishgill.htm

http://en.wikipedia.org/wiki/Gill

Answer 2

Gills are act like lungs for the fish. The cyphon the oxygen from the water to the fish.