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Table 2 Comparative developmental guide for cephalopod development

From: A practical staging atlas to study embryonic development of Octopus vulgaris under controlled laboratory conditions

Octopus vulgarisDoryteuthis pealeiSepia officinalisGeneral characteristicsStage
Adapted from Naef, 1928Arnold, 1965Boletzky, 2016  
Fertilized eggStage 1Stage 1Newly laid fertilized egg that did not finish maturationSegmentation (cleavage)
First maturation divisionStage 2Stage 1First polar bodySegmentation (cleavage)
Second maturation divisionStage 3Stage 13 polar bodiesSegmentation (cleavage)
2 cells, first cleavageStage 4Stage 2Two partially separated cellsSegmentation (cleavage)
4 cells, second cleavageStage 5Stage 3Four partially separated cellsSegmentation (cleavage)
8 cells, third cleavageStage 6Stage 4Eight incompletely separated cellsSegmentation (cleavage)
16 cells, fourth cleavageStage 7Stage 52 completely closed blastomeres, 14 blastoconesSegmentation (cleavage)
32 cells, fifth cleavageStage 8Stage 612 blastomeres, 20 blastoconesSegmentation (cleavage)
64–66 cells, sixth cleavageStage 9Stage 736 blastomeres, 28 blastoconesSegmentation (cleavage)
Stage IStage 10Stage 8Morula (advanced cleavage)Segmentation (cleavage)
Stage IIStage 10Stage 9BlastulaSegmentation (cleavage)
Stage IIIStage 11Stage 10Onset of epibolyGastrulation
Stage IVStage 12Stage 11–12Formation of the germinal disk (yolk envelope & embryonic proper)Gastrulation
Stage VStage 13Stage 13Epiboly continuesGastrulation
Stage VIStage 14–15-16Stage 14Mesoderm concentrations become more distinct (smooth surface)Epiboly
Stage VII.1Stage 17Stage 15Visible thickening of placodes startsEpiboly
Stage VII.2Stage 18Stage 15Primordia of mantle, eyes, mouth and arms visibleEpiboly/ Organogenesis
Stage VIIIStage 19Stage 16Mouth and eye invagination, funnel pouches and statocysts visibleOrganogenesis
Stage IXStage 20Stage 17Primordia more prominent. Funnel tube rudiments are distinctOrganogenesis
Stage XStage 21Stage 18Eye vesicles closed and sticking out. Funnel tube rudiments fuse ventrallyOrganogenesis
Stage XIStage 22Stage 19Mantle starts to grow. Funnel tube rudiments bend towards midlineOrganogenesis
Stage XII.1Stage 23Stage 20Funnel tube rudiments start to form a tube ventrally. Mantle covers 1/2nd of gillsOrganogenesis
Stage XII.2Stage 23Stage 20Funnel formed siphon at ventral extremity. Mantle bowl-shapedOrganogenesis
Stage XIIIStage 23Stage 21Formation of the funnel complete. Iris fold rudiment visibleOrganogenesis
Stage XIVStage 24Stage 22Mantle as wide as long and covers gills completelyOrganogenesis
Stage XV.1Stage 25Stage 23Mantle covers ventral margin of funnel. Inner yolk strongly constrictedOrganogenesis
Stage XV.2Stage 26Stage 24Mouth starts to internalizeOrganogenesis
Stage XVIStage 27Stage 25–26Few anterior chromatophores evident. Mouth completely covered by arm crownOrganogenesis
Stage XVIIStage 28Stage 27Mantle enlarged in relation to head. Chromatophores numerousOrganogenesis
Stage XVIII.1Stage 28Stage 27Yolk sac same size as head (Octopus & Loligo)Growth
Stage XVIII.2Stage 28Stage 27Chromatophores darkerGrowth
Stage XIX.1-XIX.2Stage 29Stage 28Pigmentation of ink sac. Eyes covered with iridophoresGrowth
Stage XX.1Stage 29Stage 29Yolk nearly depletedGrowth
Stage XX.2Stage 30Stage 30Loss of outer yolk and hatchlingGrowth