Fig. 7

Summary diagram of size and arrangement of lipid transporting cells (LTC, orange circles), hyaline spheres (HS, yellow) and granular masses (GM, red) during larval development and metamorphosis of A. mollis. Green colour of digestive system indicates active feeding on phytoplankton and lipid accumulation. Grey colour of digestive system indicates lipid use during the non-feeding period. Images of: a early auricularia, b late auricularia, c doliolaria and d pentactula; drawn at the same scale based on photographic images. In the early auricularia the GM and a few small LTC are observed. The late auricularia is a much larger larva, with an increase in the number and size of the LTC (one group circled) that have transported neutral lipids to multiple HS in the base of the larval arms. During the metamorphic transition to the doliolaria the HS release LTC to fuel the reorganization of the gut and the development of the water vascular system (primary tentacles shown in white). In the pentactula the primary tentacles are now external and HS remain in the juvenile stage to provide further nutrients for the peri-metamorphic period. The function of the GM remains unknown