The mammalian immune system appears to be the most complex of all known animal and plant immune systems. In fact, invertebrates do not possess in general most aspects and the adaptive immune system. Some creatures like fish possess some antibodies but not the full repertoire of antibodies and other factors found in mammalian systems....thus fish appear to possess a "transitional" immune system.

Mammals and humans require the adaptive immune system for survival. And even though invertebrates don't appear to require the adaptive system for survival they do display some immune responses consistent with the adaptive immune response...i.e, rejection of transplanted tissue. More recently, jawless fish do display lymphocyte type cells, consistent with an adaptive system. Is this evidence of an intermediate system? 

 

Discuss the evolution and design aspects of the immune systems found in plants, invertebrates, mammals and fish. Do fish really possess a "transitional" immune system? Do any truly "intermediate" adaptive immune systems exist? Do you see design features inherent in the invertebrate immune system which appears to function without an adaptive system?

DUE Sept 26