Flatworms may be free living or parasitic. The free living worms may be found in freshwater, sea water or in damp places on land. Parasitic worms live inside their hosts bodies in a fluid environment.
In free living planarians, there are two longitudinal excretory canals with a number of opening to the exterior on the body surface. The canals consist of numerous branched tubules. The fine ends of the tubules end in special hollow structures called flame cells.
In a flame cell, The nucleus is displaced to one side of the cell and the cytoplasm has a large hollow called the cell lumen. The lumen is continuous with the fine tubules. A bunch of flagella hangs down the lumen.
Waste products such as ammonia, carbon dioxide and water enter the flame cell from the surrounding cells. It is thought that the flagella help to propel the fluid into the tubules. From there, the fluid passes to the exterior.
No comments:
Post a Comment