1.   What is thesignificance of metanephridium thickness in the earthworm? Bespecific.
2.   Compare andcontrast the exoskeleton of the grasshopper and the crayfish. Howmight they be used differently for osmoregulation?
3.   The greengland of lobsters does not have any convoluted tubules associatedwith it as it does with the crayfish. What might be thesignificance of this difference?