Chapter 25.4, Problem 5MI

Summary Introduction

To summarize:

The characteristics of segmentation

Introduction:

Segmented worms have segments that allow for specialization of tissues and for efficiency of movement. Animals belonging to the phylum Annelida have segmented bodies. There are over 11,000 species of annelids most of which live in the sea. Annelids include earthworms, leeches and marine worms that differ from flatworms and roundworms because of their segmented bodies and coelom.

Answer to Problem 5MI

  

Explanation of Solution

The body of an annelid is divided into segments. Externally the segments look like stack of coins but inside the worm the segments are divided almost completely from each other by walls of tissue called septa. These are similar to the way walls separate segments of a submarine. Each segment contains structures for digestion, excretion and locomotion. The fluid within the coelom of each segment makes a rigid support system for the worm similar to the rigidity of a water filled balloon. This rigidity creates a hydrostatic skeleton that muscles can push against.