A NEW MODEL OF PODIAL DEPOSIT FEEDING IN THE SAND DOLLAR, MELLITA QUINQUJESPERFORATA (LESKE): THE SIEVE HYPOTHESIS CHALLENGED.

The feeding mechanism of Mellita quinquiesperforata (Leske) has been examined in detail. This sand dollar is a deposit feeder, ingesting particles mostly in the range of 100-250 µm. The particles are picked out of the substrate individually by specialized long barrel-tipped podia, which form a narrow palisade surrounding the geniculate spine fields on the oral surface.

FEEDING STRUCTURES, BEHAVIOR, AND MICROHABITAT OF ECHINOCYAMUS PUSILLUS (ECHINOIDEA: CLYPEASTEROIDA).

In the Firth of Lorne, Scotland, Echinocyamus pusillus was found most abundantly in highly variable, poorly sorted substrates at depths of 10-20 m. It was common in areas exposed to extensive wave and tidal current activity, but absent in fine sediments in sheltered areas. In size, feeding mechanism, and behavior, the species is highly adapted for nestling in the interstices between relatively large pebbles.