Chapter 32, Problem 1TYK

Which phylum includes animals that have a water vascular system?

a. Echinodermata

b. Hemichordata

c. Chordata

d. Tetrapoda

e. Amniota

Summary Introduction

Introduction:

A phylum is a taxonomical level of classification of organisms that lies above taxon class and below taxon kingdom. This taxonomical level for botanical organisms is named as division. The hydraulic system that is used by the organisms for transportation of waste and food, locomotion, and respiration is the water vascular system.

Answer to Problem 1TYK

Correct answer:

The phylum Echinodermata includes the animals that have a water vascular system.

Explanation of Solution

Justification/ Explanation for the correct answer:

Option (a) is, ‘Echinodermata.’ The phylum Echinodermata includes organisms like sea urchins, sea stars, and others. These animals have a water vascular system, which is a network of canals that are filled with fluid. These tubes or canals originate from the coelom. The movement of the organism and transportation of food and waste is facilitated by the contraction and relaxation of the muscles caused by the movement of water inside the canals. Hence, option (a) is correct.

Explanation for the incorrect answers:

Option (b) is, ‘Hemichordata.’ This phylum has organisms that are bilaterally symmetrical and have a body divided into three sections, namely trunk, collar, and proboscis. The locomotion of the organisms in this phylum is facilitated by the muscular, ciliated organ present anteriorly known as proboscis. The water vascular system is unique to echinoderms. So, it is an incorrect option.

Option (c) is, ‘Chordata.’ Chordata phylum includes organisms with bilateral symmetry, a circulatory system, and metameric symmetry. These organisms are more evolved and have a dedicated system for providing motion. This system has a small amount of musculature, which helps in movement. Also, food and waste are not transported with the water vascular system, as that is exclusive to Echinodermata phylum. So, it is an incorrect option.

Option (d) is, ‘Tetrapoda.’ This phylum consists of organisms that have four limbs or pods. These include mammals, amphibians, and reptiles. The organisms in this phylum move with the help of the limbs that are present. It is an evolutionary phylum, so the movement of food and waste has a different system dedicated to performing the function. So, it is an incorrect option.

Option (e) is, ‘Amniota.’ This group is a part of the phylum Tetrapoda. The tetrapods that lay their eggs on land or the ones in which the fertilized egg remains within the body of the mother are a part of this group. Tetrapods are evolved organisms, so they do not have a water vascular system. So, it is an incorrect option.

Hence, options (b), (c), (d), and (e) are incorrect.

Conclusion

Therefore, it can be concluded that the phylum Echinodermata includes organisms that use the network of fluid-filled tubes for the contraction and relaxation of their muscles. These contractions and relaxations facilitated by the water vascular system help in certain processes, like feeding and locomotion. This system also helps in the reception of sensory stimulus and exchange of gases.