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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in situ hybridization has been widely used for research applications, including clinical cytogenetics, gene mapping, tumor biology and studies of chromosome evolution.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .