Subject: Why does the chloroplast shape differ in different types of algae?

Why does there exist a variation in the shape of choloroplast in different 
algae?Is it only a trait that was developed by these organisms in the due 
course of evolution due the morphological and photosythetic requirement or are 
there any other reasons?If the photosynthetic ability does differ due to shape 
variation, please tell me which shape is most effective as per energy 
utilisation and photosynthetic product formation?And why did these organisms 
develop that particular shape?For instance ,would a spiral chloroplast make any 
difference in the way Zygnema(stellate chloroplast)carry out photosynthesis?
Thank You for your valuable time!!!

Re: Why does the chloroplast shape differ in different types of algae?