Fig. 3. Comparison of the arm length of larvae derived from the left and the right halves of embryos dissected in the gastrula stage. (A) This larva corresponds to the six-armed pluteus derived from the left half and shows the parts of the larvae that were measured. The length of the anterolateral-arm-rod plus body-rod (al-length), postoral-arm-rod plus body rod (po-length), and the postdorsal-arm-rod (pd-length) were measured. (B) Differences in the arm length of the left and the right half larvae. The al-length on the unoperated side represents the length of the larva along the anteroposterior axis in the late larval stage. The ratio of the length of the arms on the cut side to the anteroposterior length of one larva is plotted, and the differences in arm length on the cut side between populations are shown. The plots for both the al- and the pd-lengths on the cut side of S. mirabilis show similar distributions in the group with right halves and a left rudiment, the group with left halves and a left rudiment, and the group with left halves and a right rudiment. The plots also show similar distributions for the al-length on the cut side of the H. pulcherrimus larvae in the group with left halves and a left rudiment, and the group with left halves and a right rudiment.
