Why do birds have nucleus in red blood cells?

Answer 1

Mammals evolved enucleate cells, while those of other animals did not¹.

This may be because mammals are warm blooded and usually more active than most animals, thus requiring more efficient oxygen transport² (the nucleus increases the cell's volume and thus reduces the volume-surface relationship of the cells - a larger surface area makes for more effective oxygen transport).

Answer 2

Red blood cells of mammals are theoretically more evolved and specialized to carry the maximum amount of oxygen and to do so have evolved to lose their nuclei just after they have made most of their hemoglobin. There is a price though...once the red blood cell has lost its nucleus it will live for about 120 days and die.

Answer 3

The circulatory system in birds are considered 'less advanced' than in mammals.

In mammals, nuclei are rid from RBCs to increase oxygen-carrying capacity by both increasing both number of hemoglobins that it can contain and by minimizing RBC (7-8 microns) volume to allow it to squeeze through tiny capillaries (~3-4microns).

Birds, however, compensate for higher oxygen demands by evolving a "flow-through" respiratory system, which is more efficient and is essentially interconnecting tubes to allow for continuous flow, as opposed to blind-ended alveoli found in mammals.

Answer 4

Almost all eukaryotic cells contain a nucleus, which contains their DNA, or genetic make up.

Mammalian red blood cells do not contain a nucleus, which means they cannot replicate. However, frog red blood cells usually stay in circulation longer than mammalian red blood cells because the presence of a nucleus allows for more repair.

Answer 5

Yes they do!It is pretty cool to look at under a microscope.

Answer 6

They need much space to carry oxygen.So nucleus has dissapeared.