Unlike most bony fishes, sharks maintain body fluids that are isoosmotic to seawater, so they are considered by many to be osmoconformers. Nonetheless, these sharks osmoregulate at least partially by
A) using their gills and kidneys to rid themselves of sea salts.
B) monitoring dehydration at the cellular level with special gated aquaporins.
C) tolerating high urea concentrations that balance internal salt concentrations to seawater osmolarity.
D) synthesizing trimethylamine oxide, a chemical that binds and precipitates salts inside cells.
E) possessing a special adaptation that allows their cells to operate at an extraordinarily high salt concentration.

Question

Quizplus · Accepted Answer

Sharks maintain high concentrations of urea in their blood and tissues, which helps to balance the osmolarity of their internal fluids with the surrounding seawater. This allows them to maintain an isoosmotic internal environment while still retaining valuable ions, such as sodium and chloride, that would normally diffuse out of their bodies in seawater. Sharks also use their kidneys and gills to actively excrete excess salts like sodium and chloride, which helps them maintain proper electrolyte balance.

Unlike Most Bony Fishes, Sharks Maintain Body Fluids That Are