Which term describes an organism that can tolerate a wide range of salinities and is common in estuaries?

Which term describes an organism that can tolerate a wide range of salinities and is common in estuaries?

• A. Euryhaline
• B. Stenohaline
• C. Osmoconformer
• D. Endotherm

Answer: (A)

Organisms that can tolerate a wide range of salinities are described as euryhaline. In estuaries, salinity swings as freshwater mixes with seawater, so species that are euryhaline can survive from fresher to saltier waters by adjusting their internal salt and water balance. This broad tolerance is what makes them common in these environments. By contrast, stenohaline organisms can only cope with a narrow salinity range, so they’re less able to endure the variable conditions of estuaries. Osmoconformers regulate internal osmolarity to match their surroundings but this alone doesn’t specify the breadth of salinity tolerance, and endotherms are about heat regulation, not salinity tolerance.

Organisms that can tolerate a wide range of salinities are described as euryhaline. In estuaries, salinity swings as freshwater mixes with seawater, so species that are euryhaline can survive from fresher to saltier waters by adjusting their internal salt and water balance. This broad tolerance is what makes them common in these environments. By contrast, stenohaline organisms can only cope with a narrow salinity range, so they’re less able to endure the variable conditions of estuaries. Osmoconformers regulate internal osmolarity to match their surroundings but this alone doesn’t specify the breadth of salinity tolerance, and endotherms are about heat regulation, not salinity tolerance.