Gulp!

These two motion sequences feature a ten-day bipinnaria larva of the giant sea star Pisaster giganteus capturing (above) and "swallowing" (below) some green algae. Those small, oblong, greenish, hapless cells are Chlamydomonas sp. 
P. giganteus is an indirect developer, meaning that it must feed on plankton as a larva to obtain the energy necessary to metamorphose into a juvenile sea star.

The larva traps its prey using a ring of cilia around its mouth (oral ciliary band), and transfers it to the gut with the help of additional cilia and a sphincter. Coeloms are visible on either side of the esophagus. Ventral view shot at 200X under DIC illumination.