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 (nematodes) are bilaterally symmetrical, worm-like organisms that are surrounded by a strong, flexible noncellular layer called a cuticle. Their body plan is simple. The cuticle is secreted by and covers a layer of epidermal cells.

Detailed explanation-3: -Phylum Nematoda: The Roundworms Roundworms, hookworms, and heartworms are all members of phylum Nematoda, and they are all common canine maladies.

Detailed explanation-4: -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).