Fig. 1

External morphology of studied nudibranch species and generalized scheme of cnidosac structure in respective species (indicated with apostrophe). A Cuthona nana. B Catriona columbiana. C Cuthonella hiemalis. D Diaphoreolis viridis. E Eubranchus rupium. F Tergipes tergipes. G Trinchesia ornata. H Zelentia pustulata. ac cells without NCs in cnidopore zone, cnph cnidophage, cs cellules speciale, dg digestive gland, ep epithelium, gc cells with granular compound, hc cells with chitinous spindles, he haemocoel, ic interstitial cells, lu lumen, mb body musculature, mc cnidosac musculature. Scale bars: 5 mm. Photo credits: all except C: Tatiana Antokhina, C: Alexander Semenov