Chapter 25, Problem 13A

Summary Introduction

To replace:

The correct term in the place of italicized term.

Introduction:

The parasites are the organism that live in association with the other organisms and feed on them. There are many parasitic adaptations that different organisms evolve. The round worms are intestinal parasites.

Explanation of Solution

The roundworms are the intestinal parasite that have hydrostatic skeleton and a tough cuticle. The hydrostatic skeleton work along with the longitudinal muscles (contraction and relaxation movement) of the pseudocoelom that helps in the overall movement of the animal. Hence, the term can be replaced with longitudinal.