Phylum Platyhelminthes (Flatworms) - NEET-Biology

 Phylum Platyhelminthes (Flatworms)

Important Characteristics:

• Acoelomate, triploblastic, bilaterally symmetrical organisms.

• Possess a mouth but no anus- Blind sac body plan.

• Digestive, skeletal, circulatory & respiratory systems are absent, parenchymal gland serves as hydroskeleton.

• The body is soft & dorso-ventrally flattened. It may be leaf-like ribbon-like. It is without segmentation.

• Possess the organ-system level of organization.

• The organ-system level of organization.

• The organ-system is packed in a characterize connective tissue, called parenchyma.

• The nervous system is ladder-like. It comprises the brain & two main longitudinal nerve-chords connected at intervals by transverse commissures.

• The excretory system includes characteristics of flame-cells leading into tubules that open out by one or more excretory pores.

•  Hermaphroditic, often with elaborate precautions for minimizing self-fertilization.

• Fertilization is internal. Life history often includes larval stages.

• Asexual reproduction by transverse fission occurs in some forms.

• Example- Taenia (Tapeworm), Fasciola (Liver fluke)