Kingdom Animalia – Annelida

Table of Contents

• Phylum Annelida

– Systems in Annelida

• Summary
• What’s Next?

In the previous segment of the chapter ‘Diversity in Living Organisms’, we studied about the

phylum Aschelminthes. In this segment, let us get introduced to the phylum Annelida.

What is Phylum Annelida?

• Annelida includes all the organisms which have rings all over their body.

For example, earthworms.

• Each segment has a set of organs on the inner side. These organisms have developed systems. Annelids have a cylindrical and triploblastic body which originates from all the three embryonic layers namely endoderm, mesoderm, and ectoderm.

Earthworm

• Their body encloses a true body cavity, coelom which makes annelids coelomates.
• The true body cavity has the organs inside it. These organs can be located from the segment number in the annelids.
• Many of the annelids dwell on land but most of the subphylum also inhabits marine habitation.

For example, earthworms, leeches, sandworms, lungworms, etc.

Which systems are present in annelids?

• Annelids usually have a well-evolved mouth with a few mouthparts. The digestive system is also very well developed in most of them.