OBSERVATIONS ON FEEDING METHODS IN SOME FLORIDA ASCOGLOSSANS

Feeding methods are described for 12 Florida ascoglossans. Relationshipsbetween size and shape of radular teethand dimensions of foodalgae are analysed. Feeding in a diatom-eating species (Eylsiaevelinae) is described for the first time. The suctorial feedingof Ascobulla ulla and the structure of its radula and alimentarysystem clearly reveal that it is an ascoglossan, not a cephalaspid.The very complicated method of feeding in Oxynoe spp. is consideredan evolutionary "dead end", and the branching of the digestivegland and position of pharyngeal appendices seem to indicatethat the Elysiidae did not evolve from the Oxynoidae. New anddetailed observations on feeding in Elysia ornata, Placida kingstoni,and Ercolania funerea show that after cell sap has been suckedinto the pharynx, it is returned to the algal filament. Thisprocess may be repeated once or twice before the cell sap iseventually pumped into the stomach. Cell sap is probably mixedwith saliva in the pharynx to reduce its viscosity, and thepharyngeal regurgitation facilitates withdrawal of the remainingsap. ^*Present address: Ellebjergvej 22, 1 t.h., DK-2450 CopenhagenSV, Denmark. (Received 9 June 1980;