Bio; Lecture 15; Animal Evolution

Bio; Lecture 15; Animal Evolution - Principles of Biology...

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Principles of Biology BIO U103 2/14/07 Animal Evolution Once you have a mesoderm you can develop a body cavity: Coeolum . o Formation: Begins during gastrulation There are two ways coelom forms: Schizocoelomate (schizo=split) Mesoderm initially located at the sides of the archenteron It then splits at the middle of the gut it then opens up and grows outward, forming the coelom Occurs with protostome individuals Enterocoelomate The mesoderm is initially part of the coelom The mesoderm cells behave differently than the rest of the endoderm during involution. The mesoderm separates from the primitive gut, opens up and forms around it; thus forming the coelom Forms this way in deuterostomes Both of these processes yield a coelom that looks almost exactly the same Animals can be divided by the presence or absence of a body cavity Acoelomates have a solid body (filled completely with mesoderm) and lack a body cavity Phylum platyhelminthes—flatworms
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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 15; Animal Evolution - Principles of Biology...

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