Flatworms: platyhelminthes

Description: Episode of Series “Biology program; unit 3. Animal life”. After brief views of land, fresh water, marine and parasitic flatworms, shows the important characteristics of the common planaria. These are the simplest animals with bilateral symmetry, a distinct head, a central nervous system and a substantially developed mesoderm layer. Their regenerative ability is demonstrated, showing polarity, the anterior-posterior gradient and cell dominance.