Complete separation of oxygenated and deoxygenated blood in birds and mammals is particularly useful because these animals:
Question
Complete separation of oxygenated and deoxygenated blood in birds and mammals is particularly useful because these animals:
Do not need much oxygen
Have high energy needs and maintain constant body temperature
Live only in water
Lack lungs
Answer
Have high energy needs and maintain constant body temperature
Detailed Explanation
Birds and mammals constantly use energy to maintain body temperature, so an efficient, undiluted oxygen supply from separated blood streams is especially beneficial.