�y��vlog

Finally, at :51 you see a special star-burst shaped organelle called the contractile vacuole in action.

As one would expect of a freshwater species, Microgromia has a contractile vacuole complex that gradually expands as its components fill up and fuse, and then expels its contents somehow — this appears to happen inside the test.

In some protists, the contractile vacuole simply fuses with the membrane and expels its contents, but there are also plenty of variations on the subject.

Actinophrys sol, Ehrb. a, food-particle lying in a large food-vacuole; b, deep-lying finely granular protoplasm; c, axial filament of a pseudopodium extended inwards to the nucleus; d, the central nucleus; e, contractile vacuole; f, superficial much vacuolated protoplasm.

Raphidiophrys pallida, F. E. Schultze. a, food-particle; b, contractile vacuole; c, the nucleus; d, central granule in which all the axis-filaments of the pseudopodia meet.