Chapter 26, Problem 8STP

Summary Introduction

Introduction :

Earthworms are annelids and relate to phylum Annelida that is characterized by animals with a segmented body plan. Some annelids do have a larval stage similar to that of some mollusks which suggests a shared ancestor. Annelids have bilateral symmetry such as flatworms and roundworms and two openings of the body such as roundworms.

Answer to Problem 8STP

Correct answer :

The correct answer is option (C) It leaves the earthworm’s body and forms a cocoon for developing earthworms.

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) It leaves the earthworm’s body and forms a cocoon for developing earthworms. Sperm is transferred between two worms, near the clitellum segments. The clitellum is a thickened segmental band. It creates a cocoon which hatches young earthworms from. So, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) It breaks off, allowing fragmentation to occur. Annelids asexually reproduce through fragmentation. So, this is an incorrect answer.

Option (B) It indicates whether or not an earthworm is hermaphrodite. Most annelids possess separate sexes but some are hermaphrodites, such as earthworms and leeches. So, this is an incorrect answer.

Option (D) It produces sperm and egg. Sperm was exchanged by two worms near the so-called clitellum segments. So, this is an incorrect answer.