Fig. 8

Proportion of zooids in colony over time. a Decalcified colony of Immergentia stephanieae during the peak reproductive period August to October. b Decalcified colony of Immergentia cf. suecica during the peak reproductive period of December to March. c Schematic representation of zooid proportions. During December–March, a single zooidal state does not dominate in Immergentia stephanieae colonies but in Immergentia cf. suecica autozooids and reproductive zooids are relatively abundant in the colonies. From June to July, there are relatively more autozooids and reproductive zooids in Immergentia stephanieae than in the period from December to March, while these zooids are more abundant during the peak period from August to October. For Immergentia cf. suecica a single zooidal state does not dominate from June to July and there are relatively even fewer autozooids and reproductive zooids from August to October but more zooids with degenerating and degenerated polypides or remnants of cystid walls. Abbreviations: az – autozooid, bb – brown body, dz – degenerated zooid, e – embryo, rz – reproductive zooid