Arthropods, like spiders and lobster, don't have blood like mammals do; instead, they have

Arthropods like spiders do not have blood like animals, rather they have a fluid called hemolymph  in their circulatory system. Hemolymph is found in the circulatory system of arachnids, crustaceans and insects. Molluscs too have a circulatory fluid akin to this type.

In insects, exchange of oxygen and carbon dioxide occurs in  a tracheal system which means they respire directly through their body surfaces. So the circulatory system transports nutrients but only a small portion of oxygen. 

In both insects and other arthropods as well as molluscs, hemolymph contains hemocyanin, a copper based oxygen transport molecule. 

i would say the prokaryotic cells the prokaryotic cells are less complex, are usually found only in unicellular organisms and have more limited capabilities than eukaryotic cells.