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Biology Notes 3-14-08

Biology Notes 3-14-08 - cilia to swim to a new spot to...

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Biology Notes March 14, 2008 Sponges: -Sponges are not a clade, but have similar body organization that is ancestral. -rRNA gene analysis suggests that there are three groups -They have some specialized cells but no tissues or organs. Sponge Skeleton: Spicules: Sponges have skeletal elements called spicules -Glass sponges and demosponges have spicules of silicon dioxide -Calcareous sponges have spicules of calcium carbonate Sponge Body: -The sponge body plan is an aggregation of cells around a water canal system. -Extra cellular matrix of collagen, adhesive glycoprotein, and other molecules. -Most are filter feeders; a few tray prey on protruding hook-shaped spicules. Sponge Reproduction: -Sponges reproduce asexually by budding and fragmentation. -In sexual reproduction, water currents carry sperm from one individual to another. -The embryonic sponge is held, and then released as mobile larvae that use
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Unformatted text preview: cilia to swim to a new spot to settle and develop into an adult. Ctenophore : (comb jellies) have a radially symmetrical, diploblastic body plan.-The two cell layers are separated by a thick, gelatinous mesoglea, and a complete gut.-Ctenes are comb-like rows or fused cilia; more through water by beating cilia.-All are marine and feed on small planktonic organisms. Simple life cycle – fertilized egg develops into small ctenophores. Cnidarians: include jellyfish, sea anemones, coral, and hydrozoans.-The Cnidarian gut is a sac, the gastrovascular cavity. Functions in digestion, circulation, gas exchange, and as a hydrostatic skeleton. Biology Notes March 14, 2008 Three Life Cycles of a Cnidarian:-Sessile polyp stage.-Motile medusa stage: produces gametes.-Fertilized egg develops into a free swimming ciliated larva or planula, which settles and grew into a polyp....
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Biology Notes 3-14-08 - cilia to swim to a new spot to...

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