Question

The largest RBCs have been seen in:
a. Elephant
b. Whale
c. Amphibian
d. Man

Answer 1

Although all vertebrates transport the oxygen to the tissues all over the body via red blood cells. Out of which the largest red blood cells are known to be present in the amphibians, particularly in urodele amphibians.

Complete answer:
Circulatory systems have evolved in all organisms to form the most efficient oxygen transport mechanism that is possible for the organism. The oxygen is carried by hemoglobin molecules that reside within red blood cells in all advanced species.
The amphibian heart has three chambers; it has two atria and only a single ventricle. This complicates matter because the blood accumulates oxygen in the lungs and then returns to the heart before being pumped into the rest of the circulatory system. Due to this a problem arises because blood returning to the heart from the lungs is mixed up with incoming blood from the body which causes a mixing between oxygenated and deoxygenated blood. Amphibians deal with this situation by having a very slow metabolism, and also by absorbing some oxygen through their skin.

Note: The red blood cells in amphibians are enlarged due to their adaptation. In water they absorb oxygen diffused in water through their skin; whereas to meet their oxygen requirement on land they have larger RBC’s to transfer more oxygen to the organs as no absorption through the body takes place.