A freshwater fish would be expected to
a. Pump salt out through its gills.
b. Produce copious quantities of dilute urine.
c. Have scales and a covering of mucus that reduce water loss to the environment.
d. Do all of the above.

Verified step by step guidance

1. Understand the environment: Freshwater fish live in a hypotonic environment, meaning the concentration of solutes (like salts) is lower in the surrounding water compared to the fish's body fluids. This causes water to naturally flow into the fish's body by osmosis.
2. Analyze the fish's adaptations: To maintain homeostasis, freshwater fish must regulate water and salt levels. They need to expel excess water and retain essential salts.
3. Evaluate option b: Freshwater fish produce large amounts of dilute urine to remove the excess water that enters their bodies through osmosis.
4. Evaluate option a: Freshwater fish do not pump salt out through their gills. Instead, they actively absorb salts through specialized cells in their gills to compensate for the loss of salts to the environment.
5. Evaluate option c: Scales and mucus help reduce water loss in some fish, but this is more relevant for marine or terrestrial environments. Freshwater fish are more concerned with water influx rather than water loss. Based on this analysis, determine which options are correct.

Key Concepts

Osmoregulation

Osmoregulation is the process by which organisms regulate the water and electrolyte balance in their bodies to maintain homeostasis. Freshwater fish, which live in an environment where the water concentration is higher than their bodily fluids, must actively expel excess water and retain salts to survive. This involves physiological adaptations such as specialized gills and kidney functions.

Dilute Urine Production

Freshwater fish produce large volumes of dilute urine to eliminate excess water absorbed from their environment. This adaptation helps them maintain osmotic balance by ensuring that their internal salt concentration remains higher than that of the surrounding water. The kidneys of these fish are adapted to filter out excess water while retaining necessary ions.

Protective Body Coverings

The scales and mucus covering of freshwater fish serve as protective barriers that minimize water loss and provide a defense against pathogens. The mucus layer is particularly important as it helps reduce friction and can also contain antimicrobial properties. These adaptations are crucial for maintaining hydration and overall health in a hypotonic environment.