Role of the water vascular system in Echinoderms is:

A. Respiration and Locomotion

B. Excretion and Locomotion

C. Capture and transport of food

D. Digestion and Respiration

E. Digestion and Excretion

Choose the correct answer from the options given below:

To determine the correct functions of the water vascular system in Echinoderms, let us analyze the roles of this unique system step-by-step:

The water vascular system is a distinctive and defining anatomical feature of echinoderms (such as starfish, sea urchins, and sea cucumbers). It is a network of water-filled canals branching into extensions called tube feet. This system serves several vital physiological functions:
1. Locomotion: By using hydraulic pressure, the system expands and contracts the tube feet, allowing the animal to move along the seafloor. This aligns with statement A (Locomotion).
2. Respiration: The thin walls of the tube feet facilitate the exchange of gases (oxygen and carbon dioxide) between the animal's internal fluid and the surrounding seawater. This aligns with statement A (Respiration).
3. Capture and transport of food: Many echinoderms use their tube feet to grip, handle, capture prey, and transport food particles along the ambulacral grooves to the mouth. This aligns with statement C (Capture and transport of food).
4. Excretion: While some metabolic waste diffuses out through the tube feet, echinoderms lack a true specialized excretory organ within the water vascular system itself, and statement B (Excretion) is not considered one of its primary defining roles.
5. Digestion: Digestion is handled by the digestive tract (stomach and intestines), not by the water vascular system. Therefore, statements D and E (Digestion) are incorrect.

Based on this analysis, the primary roles of the water vascular system are indeed Respiration, Locomotion, and Capture and transport of food, which correspond to statements A and C.

Therefore, the correct option is A and C Only.