Fig. 1. Representative stages in embryonic development of Hemigrapsus sexdentatus. (A) Stage 1, cleavage (morula shown). (B) Stage 2, gastrula. The clear zone is the embryo. (C) Stage 3, eyespot. Yolk is present as a single mass. (D) Stage 4. The yolk forms four lobes, the heart is beating, and chromatophores are forming. (E) Stage 5, pre-hatching. The yolk has now been reduced to two lobes. (F) Hatched zoea. Scale bars, 250 µm (A–E and F). The steps in development of H. crenulatus are similar although the eggs are smaller (see text).