Fig. 3

Stereomicroscopic images and schematic representation of ancestrula formation and colonial growth in Penetrantia clionoides from Guam and Penetrantia sp. from Roscoff, France. A–D Observation of ancestrulae of P. clionoides with intervals of days between images indicated. C On day 12 ancestrula protruded its lophophore for the first time. E–F Two different ancestrulae of Penetrantia sp. G–H Schematic representation of ancestrula–stolon complexes in P. clionoides and Penetrantia sp. respectively. Abbreviations apr – apertural rim, ast – additional stolon; b – bud; bha – bore hole aperture, ist – initial stolon, op – operculum, t- tentacle, tu - tubulet