Re: Why are grapefruit and oranges spherical in shape?

Spherical and cylindrical shapes are quite common in biology because these 
geometric forms have a high volume to surface area ratio.  Fleshy fruits 
like grapefruit and oranges are around 90% water by weight and a sphere 
holds a larger volume for its size than any other shape.  Plants are 
basically radially symmetrical organisms and cylindrical to spherical 
shapes are easily produced by their growth patterns.  However, lemons and 
limes are more football shaped showing that other similar shapes also 
work. Natural selection does not seek or produce perfect forms or 
particular forms, but instead settles on any form that works well enough.  
Thus many other fleshy fruits approximate spheres or cylinders: apples, 
pears, eggplant, zucchini, cucumber, watermelon, tomatoes, and all these 
shapes function adequately to wrap a seed or seeds in an attractive, 
rewarding package for animal dispersal.