Chapter 27, Problem 10A

Summary Introduction

To estimate:

The percentage of echinoderms that are sea cucumbers.

Introduction:

Echinoderms include classes like Asteroidea, the sea stars; Ophiuroidea, the brittle stars; Echinoidea, the sea urchins and sand dollars; Crinoidea, the sea lilies and feather stars; Holothuroidea, the sea cucumbers; and Concentricycloidea, the sea daisies. These are marine animals with radial symmetry, a water vascular system with tube feet, endoskeletons with spines and larvae with bilateral symmetry.

Answer to Problem 10A

As per the given graph we can say that approximately 15% of echinoderms are sea cucumbers.

Explanation of Solution

The following graph shows different classes of echinoderms that are found in seas.

  

As we can clearly see in the graph, the brittle stars occupy the major part of the graph. It can be estimated to occupy about 35% of the total echinoderms. The sea stars are about 25% of the total echinoderms. The sea cucumbers and the sand dollars have almost equal share. The sea lilies have least numbers; about 10%. So we can estimate sea cucumbers are about 15% of total echinoderms.