Which feature is unique to echinoderms and aids in movement and feeding?

Which feature is unique to echinoderms and aids in movement and feeding?

• A. Water vascular system
• B. Notocord
• C. Lungs
• D. Gills

Answer: (A)

Movement and feeding in echinoderms rely on a water vascular system, a hydraulic network that powers the tube feet. Seawater moves through the canal system, creating pressure that extends and retracts the feet, allowing the animal to walk and to grip surfaces or prey. This hydraulically driven set of tubes and feet enables both locomotion and manipulation of food, such as prying open shells or securing prey for consumption. The other options are not unique to echinoderms: a notochord is typical of chordates, while lungs and gills are respiratory organs found in various other groups. Because the water vascular system is distinctive to echinoderms and directly supports movement and feeding via the tube feet, it is the best choice.

Movement and feeding in echinoderms rely on a water vascular system, a hydraulic network that powers the tube feet. Seawater moves through the canal system, creating pressure that extends and retracts the feet, allowing the animal to walk and to grip surfaces or prey. This hydraulically driven set of tubes and feet enables both locomotion and manipulation of food, such as prying open shells or securing prey for consumption. The other options are not unique to echinoderms: a notochord is typical of chordates, while lungs and gills are respiratory organs found in various other groups. Because the water vascular system is distinctive to echinoderms and directly supports movement and feeding via the tube feet, it is the best choice.