Chapter 33.3, Problem 2CC

Summary Introduction

To explain: How the anatomy of Annelids can be called as “a tube within a tube”.

Concept introduction: Annelids are coelomate animals with true segmentation. They are triploblastic and bilaterally symmetrical. They are found in diverse habitats such as damp soil, mud, oceans and rock crevices.

The word annelida has been derived from Latin word ‘annuli’ which means little rings. The body of annelids is made up of a number of rings like segments called metameres. Each segment is separated from other by septa with repetition of organs in each septum. The phylum Annelida includes a number of animals such as earthworm, leeches and others.