Role of the water vascular system in Echinodermsis:A. Respiration and LocomotionB. Excretion and LocomotionC. Capture and transport of foodD. Digestion and RespirationE. Digestion and ExcretionChoose the correct answer from the options givenbelow
Answer
Role of the Water Vascular System in Echinoderms
The water vascular system is one of the most distinctive and essential features of echinoderms, a group that includes starfish, sea urchins, brittle stars, sea cucumbers, and crinoids. This system is a network of hydraulic canals unique to echinoderms, derived from the coelomic cavity, and plays a vital role in their physiology and survival.
Functions of the Water Vascular System
- Locomotion
- The water vascular system is primarily responsible for locomotion in echinoderms.
- It operates the tube feet (podia), which function by hydraulic pressure generated by the movement of water within the canals.
- By filling the tube feet with water, echinoderms can extend and retract them, allowing movement, adherence to surfaces, or even exert force (for example, to pry open prey).
- Capture and Transport of Food
- The tube feet are not only locomotory organs but also assist in capturing prey and transporting food.
- In starfish, tube feet located near the mouth help move food particles and grasp prey, transferring it towards the oral cavity for ingestion.
- Respiration
- The thin walls of the tube feet allow for gas exchange, where oxygen is absorbed from seawater and carbon dioxide is expelled.
- While not the primary respiratory structure, the water vascular system contributes to the organism’s respiration by providing a means for gas exchange through the body surface and tube feet.
Functions Not Performed by the Water Vascular System
- Excretion and digestion are not carried out by the water vascular system.
- Excretion occurs through the body wall and other excretory structures, while digestion is handled by the echinoderm’s digestive system.
- Therefore, any options suggesting excretion or digestion as functions of the water vascular system are incorrect.
Summary
The correct roles of the water vascular system include:
- Locomotion (via the tube feet)
- Capture and transport of food
- Respiration (supporting gas exchange)
Incorrect associations:
- Excretion is not a function of the water vascular system.
- Digestion is managed by the digestive system, not the water vascular system.
Correct Answer
Based on the explanations above and the options provided, the correct choices would be:
- A. Respiration and Locomotion
- C. Capture and Transport of Food
Thus, the correct answer is:
(2) A and C only