Intracellular calcium ion (Ca 2+) signaling is heavily involved in development, as illustrated by the use of a number of Ca 2+ indicators. However, continuous Ca 2+ patterns during morphogenesis have not yet been studied using fluorescence resonance energy transfer to track the Ca 2+ sensor. In the present study, we monitored Ca 2+ levels during zebrafish morphogenesis and differentiation with yellow cameleon, YC2.12. Our results show not only clear changes in Ca 2+ levels but also continuous Ca 2+ patterns at 24 hpf and later periods for the first time. Serial Ca 2+ dynamics during early pharyngula period (Prim-5-20; 24-33 hpf) was successfully observed with cameleon, which have not reported anywhere yet. In fact, high Ca 2+ level occurred concurrently with hindbrain development in segmentation and pharyngula periods. Ca 2+ patterns in the late gastrula through segmentation periods which were obtained with cameleon, were similar to those obtained previously with other Ca 2+ sensor. Our results suggested that the use of various Ca 2+ sensors may lead to novel findings in studies of Ca 2+ dynamics. We hope that these results will prove valuable for further research in Ca 2+ signaling.