ABSTRACT
Although several structural models have been proposed to explain the function and genesis of sea urchin shapes, several problems remain. Principal among these are: (i) many models assume that natural structures are optimal; (ii) models have produced only axisymmetric (regular) shapes; and, (iii) shapes produced by different models tend to be alike and fall within the observed range of variance of individual species, hence discrimination between models is difficult. The tensile pneu, often invoked to explain morphogenesis, is inadequately supported, and the dome model, although partially supported, does not explain morphogenesis at all. In the intriguing pure plate model stresses have never been analysed. An alternative analysis, using computer graphical simulation of growth, is discussed. It is suggested that after properly quantifying morphological differences, explanatory models could be better refined.
