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Excretion
As it states in Wikipedia, "As with many aquatic animals,
most fish release their nitrogenous wastes as ammonia. Some of the wastes diffuse through the gills into the surrounding water.
Others are removed by the kidneys, excretory organs that filter wastes from the blood. Kidneys help fishes control the amount
of ammonia in their bodies. Saltwater fish tend to lose water because of osmosis. In saltwater fish, the kidneys concentrate
wastes and return as much water as possible back to the body. The reverse happens in freshwater fish, they tend to gain water
continuously. The kidneys of freshwater fish are specially adapted to pump out large amounts of dilute urine. Some fish have
specially adapted kidneys that change their function, allowing them to move from freshwater to saltwater."
Respiratory
As it states in Wikipedia, "Most fish exchange gases by using gills
that are located on either side of the pharynx. Gills are made up of threadlike structures called filaments. Each filament contains a network of capillaries that
allow a large surface area for the exchange of oxygen and carbon dioxide. Fish exchange gases by pulling oxygen-rich
water through their mouths and pumping it over their gill filaments. The blood in the capillaries flows in the opposite direction
to the water, causing counter current exchange. They then push the oxygen-poor
water out through openings in the sides of the pharynx. Some fishes, like sharks
and lampreys, possess multiple gill openings. However, most fishes have
a single gill opening on each side of the body. This opening is hidden beneath a protective bony cover called an operculum. Juvenile bichirs have external gills, a very primitive feature that they hold in common with larval amphibians.Many fish can breathe air. The mechanisms for doing so are varied. The skin of anguillid
eels may be used to absorb oxygen. The buccal cavity of the electric eel
may be used to breathe air. Catfishes of the families Loricariidae,
Callichthyidae, and Scoloplacidae are able to absorb air through their digestive tracts. Lungfish and bichis have paired lungs similar to those of tetrapods and must rise to the surface of the water to gulp fresh air in through
the mouth and pass spent air out through the gills. Gar and bowfin have a vascularised swim bladder that is used in the same way. Loaches, trahiras, and many
catfish breathe by passing air through the gut. Mudskippers breathe
by absorbing oxygen across the skin (similar to what frogs do). A number of fishes have evolved so-called accessory breathing
organs that are used to extract oxygen from the air. Labyrinth fish (such as gouramis and bettas) have a labyrinth
organ above the gills that performs this function. A few other fish have structures more or less
resembling labyrinth organs in form and function, most notably snakeheads,
pikeheads, and the Clariidae family of catfish.
Being able to breathe air is primarily of use to fish that inhabit shallow, seasonally
variable waters where the oxygen concentration in the water may decline at certain times of the year. At such times, fishes
dependent solely on the oxygen in the water, such as perch and cichlids, will quickly suffocate, but air-breathing fish can
survive for much longer, in some cases in water that is little more than wet mud. At the most extreme, some of these air-breathing
fish are able to survive in damp burrows for weeks after the water has otherwise completely dried up, entering a state of
aestivation until the water returns.
Fish can be divided into obligate air breathers and facultative air breathers. Obligate air breathers,
such as the African lungfish, must breathe air periodically or they will suffocate. Facultative air breathers, such
as the catfish Hypostomus plecostomus, will only breathe air if they need to and will otherwise rely solely on their
gills for oxygen if conditions are favourable. Most fish are not obligate air breathers as there is an energetic cost in rising
to the surface and a fitness cost of being exposed to predators."
Compare & Contrast
FIshes need oxygen just like humans to survive. They have very similar
organs like us which have the same role(s)like ours. Their respiratory system is similar to ours. The organs arent the same
but the way it functions is sorta similar. Like it delivers oxygen to thier blood cells and their veins and arteries are located
close to the gills like ours are located near the lungs. Their digestive system is similar to ours also. Where the esophagus begins
to break down the food and then after the stomach breaks the food with enzymes. The last step is the intestine just
like ours. The pyloric caeca which are fingerlike pouches absorbs the nutritions. Fishes also have organs which we don't
have like gills or a swim bladder. Also fishs are cold-blooded while we are warm-blooded.
How do the differences benefit to the organism in its environment?
Since fishes
live under water and they can't just breathe the oxygen like we do. They need gills to remove the oxygen from the water they
take in. Its a good thing they have gills instead of lungs because if they didn't then it for them it would be very hard to
survive. The structure of a fish also benefits the fish because it makes the fish swim easily and also fast if trouble ever
occurs.
Website created by:
 Shebaz Ali,
 Danny Cokes,  Daniel S.
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