Final answer:
Marine organisms employ a variety of osmoregulatory strategies to maintain osmotic balance. Not all marine vertebrates have higher internal osmolarity compared to surrounding seawater. The correct option is E.
Step-by-step explanation:
The assertion that all marine vertebrates have a higher internal osmolarity than that of the surrounding seawater is not entirely accurate. While many marine organisms do face the challenge of maintaining osmotic balance in an environment that has a higher solute concentration, not all marine vertebrates have higher internal osmolarity.
For example, marine iguanas such as Amblyrhynchus cristatus expel excess salt through sneezing, aligning solute concentrations within acceptable internal levels. Conversely, many marine invertebrates have isotonic internal salt levels to their environments, preventing the continuous water loss or gain through osmosis.
Saltwater fish, being in a hypertonic environment, excrete salt through their gills and produce highly concentrated urine to maintain osmotic balance and are thus not necessarily having higher osmolarity than seawater.
Importantly, cartilaginous fish like sharks utilize organic compounds such as urea and trimethylamine oxide (TMAO) to achieve isotonicity with seawater, storing large concentrations of urea to maintain the balance rather than having a higher osmolarity. The osmolality of their body fluids is the same as their seawater environment.
Most marine invertebrates are osmoconformers. This means that:
A. the osmolality of their body fluids is equal to that of the osmoregulators who inhabit the same environments.
B. the osmolality of their body fluids fluctuates between being hypertonic to hypotonic depending on the season and the tides.
C. the osmolality of their body fluids is not the same as their seawater environment.
D. the osmolality of their body fluids is the same as their seawater environment and that their bodies contain the same solutes as their surroundings.
E. the osmolality of their body fluids is the same as their seawater environment.