EVERYDAY SCIENCE

Detailed explanation-1: -Roundworms: Phylum Nematoda. Species in the phylum Nematoda (from the Greek root word nema meaning thread) are better known as the roundworms (Fig. 3.41). There are about 25, 000 species of nematodes formally described by scientists.

Detailed explanation-2: -Roundworms, hookworms, and heartworms are all members of phylum Nematoda, and they are all common canine maladies.

Detailed explanation-3: -The examples of nematodes are roundworm (Ascaris), hookworm (Ancylostoma).

Detailed explanation-4: -Earthworm is placed in the phylum Annelida. Eventhough they are triploblastic and bilaterally symmetric organisms, they do possess a true body cavity hence are not placed in Nematoda.

Detailed explanation-5: -All nematode species are endoparasitic. They are called roundworms because they appear circular in cross-section. It includes Ascaris (Round worm) and Wuchereria (Filarial worms), Enterobius (Pin worm), Ancylostoma (Hook worm).