Biology Notes - Cnideria Saturday, March 13, 2010 5:13 PM...

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There are Hyrozoa - most marine, few freshwater, both polyp n medusa in most. Polyp often colonial Screen clipping taken: 3/13/2010 5:17 PM Phylum Ctenophora - comb jellies Ctene are cilia on these organisms. They have what is called a aboral sense organ. It is a statolith, a calcium carbonate molecules that inserts certain pressures on individual 4 nerve cells that control the ctene. This makes the ctene beat faster to become more upright. This is a balance mechanism that helps keep the organism upright. This is just like our inner ear. The fluid puts pressure. These organisms have the ability to bioluminescence . They use this to stop predators. It works like when you take a hamburger, you would not eat it if it started glowing. Phylum Platyhelminthes These are acoelomates. They are mostly predatory and have few free living ones. These are referred to as flatworms. They have only one opening to their gut tube. Food coming in has to be digested and consumed. They have more organ systems. The group is divided into 4 different classes. They are the Turbllaria - free living, most have full development of body systems. Cestoda - they do not have a digestive system. They just need to absorb these nurtients from their hosts that is already digested. They lack heads and break out after fertilizaiton. They are acelomates that don’t have a respiratory system and use simple fusion for gas exchange and many other purposes. They have a tripartate gut that is developed into 3 parts that are in 3 different directions. Their mouth is in the middle of the body and comes out of the body and feeds. They push the food through the muscular pharynx and distribute it around. Any undigested food is taken back out through the pharynx. They also have a protonephridia are flame cells. These organisms are hypertoni c and has water coming in. So protonephridia remove excess fluid, not excess water. They are not selective on what they excrete. Cnideria Saturday, March 13, 2010 5:13 PM New Section 1 Page 1
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They have cilia arround it that move the fluid. They have a problem since they do not have a proper filtration system it removes whatever fluid it gets. They have a nephreidiopore that removes the fluids. This does not select for or against any fluids. They remove interstitial fluid, fluids between cells. Their reproduction is also important. They have ovaries and testes. They are hermaporodites. They are simultaneous hermaphrodites. Both sets of reproductive organs are able to reproduce simultaneously.
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Biology Notes - Cnideria Saturday, March 13, 2010 5:13 PM...

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