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 are balanced with internal salt concentrations to seawater osmolarity
D) synthesizing trimethylamine oxide, a chemical that binds and precipitates salts inside cells

Question

Quizplus · Accepted Answer

Sharks tolerate high urea concentrations that are balanced with internal salt concentrations to seawater osmolarity. This is an adaptation that allows them to maintain their body fluids isoosmotic to seawater, without expending a lot of energy. The high urea concentrations in their blood also act as an osmotic buffer, preventing water loss through their gills and skin. However, they still rely on their gills and kidneys to regulate their internal salt concentrations to some extent.

Unlike Most Bony Fishes, Sharks Maintain Body Fluids That Are