Explain how the water vascular system allows an echinoderm to move along the ocean floor. Please help!

Sea stars move using a water vascular system. Water comes into the system via the madreporite. It is then circulated from the stone canal to the ring canal and into the radial canals.

Explanation: The radial canals carry water to the ampullae and provide suction to the tube feet.

Water gets into the water vascular system through an opening in the echinoderm's body. When the animal contracts its muscles, the water is forced through the system and into the tube feet. The tube feet act as suction cups, gripping the surface below. When the echinoderm retracts its muscles, the tube feet retract and let go of the surface. This series of contractions and retractions allows the animal to move along the ocean floor.

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b. the carbon cycle ensures living things have a source of hydrogen

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.