Bio; Lecture 18; Animal Evolution

Bio; Lecture 18; Animal Evolution - Principles of Biology 2...

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Principles of Biology 2 BIO U103 February 22, 2007 Digestive Tract o No digestive tract—cellular digestion Cells consume food via phagocytosis Porifera o Blind Sac No exit to gastric cavity Cnidaria, platyhethimis o Tube within a tube No digestive tract o Intercellular digestion o Prevalent in sponges (porifera) o Water goes into the spongocoel o Choanocyte cells which line this space draw food particles with cilia o Food is moved toward amoebocytes Blind Sac o Occurs with Cnidaria o Digestion is also extracellular o Cnidaria are also dipoblastic They do not have muscle tissue—which forms from mesoderm o Blind sac is called the gastrovascular cavity . o Gastrovascular cavity is lined with gastrodermis . Produces digestive enzymes into the cavity These break down whatever food is in there Nutrients are spread throughout cells along the gastrovascular cavity Body is only 2 cells thick o Mesoglia : space between epidermis and gastrodermis o Planaria
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This note was uploaded on 05/26/2008 for the course BIO 103 taught by Professor Potts-santone during the Spring '07 term at Northeastern.

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Bio; Lecture 18; Animal Evolution - Principles of Biology 2...

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