Why does a freshwater fish produce lots of urine?

An alternative set of physiological mechanisms allows freshwater fish to concentrate salts to compensate for their low salinity environment. They produce very dilute, copious urine (up to a third of their body weight a day) to rid themselves of excess water, while conducting active uptake of ions at the gill.

How do freshwater fish excrete urine?

Fish urinate either through their gills or through a “urinary pore.” The latter eliminates urine that has been filtered via the kidneys. Saltwater varieties excrete most urine through the gills, while freshwater fish do so through the urinary pore.

How do fishes urinate?

Like you, fish have kidneys. Kidneys help the body make urine. The shape and size of kidneys can be different depending on the species. A lot of fish get rid of the pee through an tiny opening, called a pore, that’s near their rear ends—and in some fish, waste also goes out through the skin or the gills.

Do fishes have urinary bladder?

A urinary bladder is present in fish as an expansible part of the urinary duct, in amphibians and bladder-possessing reptiles (Sphenodon, turtles, most lizards) as a pocket in the cloaca.

Do fish excrete urine?

Freshwater fish will passively intake water from their environment and then, as their insides are saltier than their surroundings, will excrete a diluted urine. Fish have kidneys which produce urine containing ammonium, phosphorus, urea, and nitrous waste.

How do fish excrete?

Marine fishes must conserve water, and therefore their kidneys excrete little water. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.

How does fish pee?

What is urine produced by?

kidneys: two bean-shaped organs that filter waste from the blood and produce urine. ureters: two thin tubes that take pee from the kidney to the bladder. bladder: a sac that holds pee until it’s time to go to the bathroom.

How does a fish excrete?

How freshwater fish excrete ammonia?

Freshwater fish mostly excrete ammonia with only a small quantity of urea. A closely related species that lives in water at pH 7.1 lacks these enzymes and excretes mainly ammonia with small amounts of urea produced via uricolysis. It dies within 60 min when placed in water from Lake Magadi.

Do fish have urinary bladders?

Why do freshwater animals produce copious urine?

To void their excess of water, freshwater animals produce a copious urine. In nearly all freshwater animals, the urine is dilute compared with the blood plasma. The dilute condition of the urine helps to maintain not only the blood osmotic pressure but also blood concentrations of major ions at levels higher than those in the environment.

Do marine mammals have a high concentration of urine?

Marine mammals lack salt glands but have kidneys that can produce more-concentrated urine than reptiles (including birds). Their urine-concentrating abilities are not exceptional compared with those of other mammals, however, and their water–salt balance is not entirely understood.

How do fish replace lost ions in urine?

To replace ions lost by direct diffusion into the environment and excretion in urine, freshwater animals take up Na+, Cl–, and some other ions by active transport. The gill epithelium is the principal site of active ion uptake in adult teleost fish and crayfish. Foods also help to replenish ions.

Why do freshwater animals gain and lose water by osmosis?

In contrast to marine organisms, freshwater animals are constantly gaining water by osmosis and losing salts by diffusion. This happens because the osmolarity of their internal fluids is much higher than that of their surroundings.