| 11. | It is joined to the radial canals which extend to the margin of the bell, where tentacles are attached.
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| 12. | Digestion begins in the center of the manubrium, which communicates with the four radial canals and the ring canal.
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| 13. | In between each radial canal, in many sea star species, there lies a muscular sac called a polian vesicle.
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| 14. | The radial canal ends in a small water-filled tentacle which protrudes through the uppermost plate of the ambulacral region.
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| 15. | Ophiuroids have no ambulacral groove, and the radial canals instead run through the solid bone-like ossicles of the arms.
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| 16. | The gonads are beside the radial canals, except in " Limnocnida ", where they are on the manubrium.
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| 17. | Each side of the radial canals gives rise to a row of bulb-like ampullae, which are connected via lateral canals.
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| 18. | The five radial canals run into the arms and branch several times to supply all of the individual branches and pinnules lining the arms.
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| 19. | Four radial canals connect the stomach to an additional, circular canal running around the base of the bell, just above the tentacles.
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| 20. | The medusae, or jellyfish, are solitary animals, with tentacles arising from the bell margin, lacking statocysts but possessing radial canals.
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