Kidneys in Fish
Throughout all organisms, the function of the kidneys generally is to ensure that osmoregulation is kept constant. That is that the water and salt balances within the bodies of the organisms are kept at the appropriate level needed for the organism to survive. When it comes to fish especially, the kidneys are designed to interact with the internal body fluids on how they interact with external water fluids. Therefore the kidneys function slightly differently between those fish that live in saltwater and those that live in freshwater.
The kidneys in fish are slightly different to those found in mammals. They are smaller, stretched and do not resemble beans as such. Generally, within fish, the kidney is located towards the very middle of the fish both lengthwise and heightwise.
The kidneys in fish are slightly different to those found in mammals. They are smaller, stretched and do not resemble beans as such. Generally, within fish, the kidney is located towards the very middle of the fish both lengthwise and heightwise.
Freshwater Fish
Within freshwater fish, the kidney is responsible for preventing excess solute loss as they contain more salts within their blood than the water located around thier bodies. Due to this concentration gradient, water will naturally diffuse into the fish through osmosis causing large amounts of water to build up inside. Therefore, the kidneys in this type of fish increase the amount of water that passes out in their urine and actively reabsorb the salts that would pass out as well to maintain that balance. This therefore results in the production and excretion of large amounts of dilute urine. This urine is so dilute that it is almost completely composed of water.
Within freshwater fish, the kidney is responsible for preventing excess solute loss as they contain more salts within their blood than the water located around thier bodies. Due to this concentration gradient, water will naturally diffuse into the fish through osmosis causing large amounts of water to build up inside. Therefore, the kidneys in this type of fish increase the amount of water that passes out in their urine and actively reabsorb the salts that would pass out as well to maintain that balance. This therefore results in the production and excretion of large amounts of dilute urine. This urine is so dilute that it is almost completely composed of water.
Saltwater Fish
Saltwater fish are almost the complete opposite when it comes to kidney function as the water and liquid around them is highly concentrated with salts and other solutes. This means that the water within the fish is constantly being 'sucked out' of them into the surrounding water through osmosis. This is because the fluids inside their bodies are less concentrated than the saltwater around their bodies. Therefore the fish must counteract this process through drinking water and the use of their kidneys. By constantly intaking water, the benefits include that the fish is constantly replacing the water that is sucked out of it however, this can lead to an extreme intake of salts and build up of harmful substances within the fish. These salts are removed through the use of the kidneys whereby they help the fish retain water and actively excrete salts to produce a very concentrated urine. This also means that saltwater fish do not urinate as much excrement as does freshwater fish.
Saltwater fish are almost the complete opposite when it comes to kidney function as the water and liquid around them is highly concentrated with salts and other solutes. This means that the water within the fish is constantly being 'sucked out' of them into the surrounding water through osmosis. This is because the fluids inside their bodies are less concentrated than the saltwater around their bodies. Therefore the fish must counteract this process through drinking water and the use of their kidneys. By constantly intaking water, the benefits include that the fish is constantly replacing the water that is sucked out of it however, this can lead to an extreme intake of salts and build up of harmful substances within the fish. These salts are removed through the use of the kidneys whereby they help the fish retain water and actively excrete salts to produce a very concentrated urine. This also means that saltwater fish do not urinate as much excrement as does freshwater fish.