| Stage 0 | Cleavage |
| Stage I | Morula (advanced cleavage) |
| Stage II | Blastula; disk flatter |
| Stage III | Onset of epiboly |
| Stage IV | Formation of the germinal disk, as wide as the yolk |
| Stage V | Epiboly reaches 1/4th of the yolk |
| Stage VI | Epiboly reaches 1/2nd of the yolk |
| Stage VII.1 | Epiboly reaches 3/4th of the yolk |
| Visible thickening of placodes starts |
| Stage VII.2 | Embryo completed first reversion |
| Primordia of eyes, mouth, mantle and arms clearly visible |
| Stage VIII | Mouth and eye invagination |
| Mantle elevated and embryo thicker |
| Funnel pouches visible in lateral view |
| Stage IX | First eye pigmentation (yellowish) |
| Primordia more prominent |
| Funnel tube rudiments are distinct |
| Contraction of yolk envelope evident |
| Stage X | Mantle flat, no depression in the middle |
| Eye vesicles sticking out with light orange retina (“saddle” shape) |
| Funnel tube rudiments fuse at the ventral margins |
| Stage XI | Mantle tilted |
| Funnel tube rudiments bended towards midline |
| Arm buds ‘elevated’ from yolk |
| Stage XII.1 | Mantle thicker and covers 1/2nd of gills |
| Funnel tube rudiments start to form a tube ventrally |
| First suckers recognizable on the posterior side |
| Stage XII.2 | Mantle bowl-shaped |
| Funnel formed siphon at ventral extremity |
| Stage XIII | Mantle is bigger |
| Formation of the funnel complete |
| Arms elongated and pointed with (3) prominent suckers |
| Stage XIV | Mantle as wide as long and cube-shaped, covers gills completely |
| Heartbeat starts |
| Embryo and yolk have equal size |
| Stage XV.1 | Mantle completely covers ventral margin of funnel |
| Inner yolk strongly constricted (connection inner and outer yolk sac very thin) |
| Appearance of two chromatophores laterally from the funnel |
| Stage XV.2 | Mouth encircled by anterior arms |
| First chromatophores on posterior mantle appear |
| Stage XVI | Mouth completely covered by arm crown |
| Yolk size 1/3rd of embryo + yolk |
| Few chromatophores on anterior mantle evident |
| Stage XVII | Chromatophores darker and more numerous |
| Stage XVIII.1 | Yolk size 1/4th of embryo + yolk |
| Posterior chromatophores darker and chromatophores appear next to the eye |
| Embryo more active in egg (mantle contraction) |
| Stage XVIII.2 | Anterior chromatophores darker. Chromatophores react to light stimulus |
| Stage XIX.1 | Eyes tilted and covered with iridophores |
| Yolk size 1/6th of embryo + yolk |
| Embryos react to mechanical stimulus |
| Pigmentation of ink sac |
| Stage XIX.2 | Embryos completed second reversion |
| Stage XX.1 | Minimal outer yolk sack |
| Chromatophore expansion and contraction more widely distributed |
| Stage XX.2 | Absence of outer yolk |
| Hatching |
