Figure 2From: Origin and evolutionary plasticity of the gastric caecum in sea urchins (Echinodermata: Echinoidea)List of higher sea urchin taxa analyzed in this study. Note that the monophyly of several of these taxa is still under debate. The numbers in brackets designate the number of species analyzed in each family in the course of this study. This diagram is based upon results obtained by numerous authors [74–84].Back to article page