Explain general characteristics of phylum Platyhelminthes and Nematoda. Give two examples of each.

Characteristics of phylum Platyhelminthes:

(1) They have dorso-ventrally flattened body, hence are called flatworms.

(2) Flatworms are bilaterally symmetrical, triploblastic and acoelomate animals.

(3) They have organ level of body organization.

(4) They are either freeliving or parasitic.

(5) Hooks and suckers are present in the parasitic forms.

(6) Flame cells are found for osmoregulation and excretion.

Examples- Taenia (Tapeworm), Fasciola (Liver fluke).

Characteristics of phylum Nematoda:

(i) They are known as roundworms.

(ii) They may be freeliving, aquatic and terrestrial or parasitic in plants and animals.

(iii) The nematode body is also bilaterally symmetrical and triploblastic.

(iv) They have organ-systme level of body organization.

(v) They are pseudocoelomate animals.

(vi) Sexes are separate (dioecious), i.e., males and females are distinct.

(vii) Roundworms have organ-system level of body organization.

Examples- Ascaris (Round Worm), Wuchereria (Filaria worm