oceans current plays a huge role on determining where the organism will move. Although some species appear to be sessile, all cnidarians are motile to some degree (such as sea anemones, see left). There are both advantages and disadvantages of how these organisms move. The lack of inner structures (bones etc.) makes it very difficult for predators to grab a hold of. Also, it is very light and agile, and water current allows for greater genetic diversity when reproducing. However, the structure is very fragile. In a storm, various cnidarians are quite vulnerable to being washed up on shore, or forced out of their habitat/niche.
Wednesday, February 14, 2007
Movement + Response to Environment
Most cnidarians use their fluid filled body cavity as a hydrostatic skeleton. Muscle surrounding the cavity contracts and relaxes, causing the incompressible liquid to be pushed back and forth. As water moves in one direction, the cnidarian moves the opposite way. Because most cnidarians do not have a central nervous system, they rely on sense organs to determine whether they are near a predator, moving up or down, and towards or away from light. The 
oceans current plays a huge role on determining where the organism will move. Although some species appear to be sessile, all cnidarians are motile to some degree (such as sea anemones, see left). There are both advantages and disadvantages of how these organisms move. The lack of inner structures (bones etc.) makes it very difficult for predators to grab a hold of. Also, it is very light and agile, and water current allows for greater genetic diversity when reproducing. However, the structure is very fragile. In a storm, various cnidarians are quite vulnerable to being washed up on shore, or forced out of their habitat/niche.
oceans current plays a huge role on determining where the organism will move. Although some species appear to be sessile, all cnidarians are motile to some degree (such as sea anemones, see left). There are both advantages and disadvantages of how these organisms move. The lack of inner structures (bones etc.) makes it very difficult for predators to grab a hold of. Also, it is very light and agile, and water current allows for greater genetic diversity when reproducing. However, the structure is very fragile. In a storm, various cnidarians are quite vulnerable to being washed up on shore, or forced out of their habitat/niche.
