Question

In which phylum is the water vascular system found?
A. Protozoa
B. Arthropoda
C. Porifera
D. Echinodermata

Answer 1

The water vascular system is found in that phylum which includes marine invertebrates that show radial symmetry such as starfish, sea cucumbers, brittle star, etc. This phylum consists of a network of fluid-filled canals that is derived from the body cavity and helps in the gaseous exchange, locomotion, feeding, and sensory reception.

Complete answer:
Option (A) is incorrect. Phylum Protozoa include organisms that have a simple body organization and do not possess a water vascular system. Their locomotory organs include flagella, cilia, pseudopodia, or none.
Option (B) is incorrect. Phylum Arthropoda includes organisms that have segmented bodies and jointed limbs. This phylum possesses an open circulatory system for the transport of oxygen and the water vascular system is absent.
Option (C) is incorrect. Phylum Porifera includes pore-bearing first multicellular animals. This phylum does not possess a water vascular system for gaseous exchange instead, gaseous exchange and the process of excretion takes place by the process of diffusion.
Option (D) is correct. Phylum Echinodermata includes organisms that have a well-developed water vascular system. This system has canals that are connected to numerous tube feet to push the organism against the ground. The water vascular system acts as a hydraulic system that is used for locomotion, respiration, and food and waste transportation.

Hence, the correct answer is option (D).

Note: Echinoderms exhibit organ level of organization and include only marine animals i.e., freshwater and terrestrial organisms are not found. These organisms are spiny-skinned and have a star-like appearance. Tube feet aid in locomotion and the presence of a water vascular system is the characteristic feature of echinoderms.