BIOL 2003 Lecture Notes - Lecture 7: Mesoderm, Ectoderm
1 Oct 2015
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Document Summary
Most get the through gut, not blind ended: ectoderm gives rise to nervouse system and sense organs, mesoderm gives rise to connective tissues, bones, muscles, blood vessels, endoderm gives rise to various internal organs including lining of gastro tract. Having a mesoderm means having body cavities: purpose for hole and central cavity is the gut, mesoderm surrounds the tube of the gut, diploblasts have no true body cavity fluid filled cavity from the endoderm forms the gastrocoel to give a blind ended gut, recap; acoelomate, pseudocoelomate, eucoelomate, cephalization. Examples of early sensory systems: statocyst; balancing sensory receptor helps with orientation, statolith inside, covered in cilia when animal moves the cilia are triggered and relay direction back to the motor control of the animal. 350 species: have no coelom, the first bilaterians, exclusively marine, tiny; live interstitially between sand grains, have a statocyst, no anus, no gut.
