Chapter 25.2, Problem 5MI

Summary Introduction

To organize:

The information about roundworms by filling in chart.

Introduction:

Roundworms are the most commonly found parasites found everywhere. They are primitive organisms, having no respiratory or circulatory system. They have a hollow body with two openings at the ends.

Answer to Problem 5MI

The information about roundworms is given in the table below:

Phylum: Nematoda	Symmetry: Bilateral
Habitats: Cosmopolitan in distribution. They are present everywhere from marine and freshwater habitats to land; some are parasites on plants and animals.
Body shape: They are cylindrical, unsegmented, tapered at both ends.
Food: Some roundworms are feed on tiny invertebrates, others feed on decaying plant and animal matter, some feed on living hosts.
Digestive tract of free-living forms: They eat trough mouth and wastes exiting through the anus.
Circulatory and respiratory organs: Not present, they depend on diffusion for moving nutrients and gases throughout the body.
Stimuli they can detect: They detect touch and chemicals and some can detect differences between light and dark.
Reproduction method: Sexual	Type of fertilization: Internal

Explanation of Solution

Roundworms are omnipresent. They maybe free -living, aquatic and terrestrial or parasitic on plants and animals. they are cylindrical, unsegmented, tapered at both ends and have organ-system level of body organization. They are bilaterally symmetrical and triploblastic animal. Alimentary canal is complete, at one is mouth and anus on the other end with a well developed muscular pharynx. circulatory and respiratory organs are absent. the excretory waste is removed from the body cavity through the excretory pore. They can can detect touch and chemicals stimuli and some can detect differences between light and dark. Sexes are separate, fertilization is internal and development may be direct.