| 1. | They are part of the water vascular system.
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| 2. | The water vascular system, haemal system and perihaemal system form the tubular coelomic system.
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| 3. | The structure of the water vascular system contains several calcareous parts before moving to the podia.
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| 4. | Some of the body cavities degenerate but others become the water vascular system and the visceral coelom.
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| 5. | Like other echinoderms, basket stars lack blood and achieve gas exchange via their water vascular system.
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| 6. | Like other echinoderms, crinoids possess a water vascular system that maintains hydraulic pressure in the tube feet.
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| 7. | Once the tube feet develop from the water vascular system, the larva frees itself from the bottom.
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| 8. | However, no stereom or internal structure showing a water vascular system is present and the identification is inconclusive.
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| 9. | The movement of the tube foot depends on the hydraulic pressure of the water vascular system, and individual muscle action.
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| 10. | This is a skeletal plate, or sieve, opening to the water vascular system, located on the aboral surface.
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