Chapter 27.1, Problem 6MI

Summary Introduction

To sequence:

The steps that occur in the water vascular system to enable an echinoderm to move by completing the given flow chart.

Introduction: Animals belonging to the phylum Echinodermata have unusual characteristics that distinguish them from animals of other phyla. These animals are found in all the oceans of the world. They move by means of hundreds of hydraulic, suction- cup- tipped appendages and have skin covered with tiny pincers.

Answer to Problem 6MI

Explanation of Solution

An important feature of all echinoderms is their water vascular system- systems of fluid- filled closed tubes that work together enable echinoderms to move and get food. There is a strainer like opening to the water vascular system known as a madreporite. Water is drawn into the madreporite, and then moves through the stone canal to the ring canal. From there water moves to the radial canals and finally to the tube feet.

Tube feet are small, muscular fluid filled tube that ends in suction- cuplike structure and is used for movement, food collection and respiration. The opposite end of the tube feet is a muscular sac called the ampulla. When the muscles contract in the ampulla water is forced out into the tube feet and it extends. The suction cup- like structure on the end of the tube feet attaches it to the surface. This hydraulic suction enables all echinoderms to move.

Hence the correct sequence of steps is:

C-> B->F-> D-> A-> E