Chapter 25.4, Problem 3MI

Summary Introduction

To define:

The given terms.

Introduction:

The terms given in the question are associated with annelids such as earthworm. Annelids are coelomate and triploblastic segmented animals. They exhibit organ level organization. they have well developed excretory, circulatory and digestive systems.

Answer to Problem 3MI

The definition of the terms given in the table below:

Term	Definition
Crop	A part of the worm’s digestive tract where food is stored before passing on to the gizzard.
Setae	Tiny bristles located on each segment that push into the soil and anchor the worm during movement.
Gizzard	A muscular sac containing hard particles that help grind soil and food before they pass into the intestine.
Clitellum	A thickened band of segments that produces a cocoon from which young earthworms hatch.

Explanation of Solution

Crop: It is a part of alimentary can in annelids such as earthworm. It is a place where food and soil taken in by the mouth are stored before passing on to the gizzard.

Setae: They are tiny bristles made of chitin located on the body of an earthworm. These are helpful in locomotion. Setae help the earthworm to hold the surface

Gizzard: A muscular sac which contains small stones the earthworm swallows. The stones act as a grinder, helping to smash up the soil and organic material before they pass into the intestine.

Clitellum: It is the ring-shaped, non- segmented glandular tissue or region in the body of annelids. It secretes viscous fluid to form a cocoon for its eggs.