THE FEEDING MECHANISM IN THE SAND DOLLAR MELLITA SEXIESPERFORATA (LESKE)

Abstract

M. sexie-sperforata lives in the surface layers of sand in shallow water. It is a microphagous feeder, Sand is pushed onto the aboral surface and sorted by club-shaped spines. Fine particles drop down between the spines and are carried round to the oral surface by ciliary currents, thence to the ambulacral grooves where a food cord is formed and transported to the mouth by podia. Other podia all over the oral surface play an accessory role in food gathering. Mucus is probably secreted by miliary spines on the aboral surface. Defecation is an intermittent process and feeding stops while it is in progress.