| 
Mammalian RBC | 
Non-mammalian RBC | 
| 
1.     
  Spherical or
  biconcave | 
Oval and biconvex | 
| 
2.     
  Nucleus is lost
  during maturation so called enucleated | 
Nucleus present
  throughout the life | 
| 
3.     
  Most of the cell
  organelles are absent | 
Present | 
| 
4.     
  Anaerobic metabolism | 
Aerobic metabolism | 
| 
5.     
  More amount of
  haemoglobin | 
Less amount of
  haemoglobin | 
| 
6.     
  Transportation of
  more oxygen and CO2 | 
Less oxygen is
  transported by blood |