BIO 2129 Final: Final_Exam_-_Porifera.doc
1 Dec 2014
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Document Summary
Cellular grade of organization: multicellular animals, animals organized at the cellular grade. Eggs can form from archaeocytes or choanocytes and are fertilized by sperm formed from choanocytes and released into the water as it flows out of the sponge. After capturing sperm, the choanocyte looses its flagella and collar becoming amoeboid to carry the sperm to the egg. A variety of different ciliated larval stages appear in sponges but all swim away from the parent sponge and settle to form a new adult sponge. These changes will result in the cell carrying out new functions. / meaning each of the cell types can, if needed, differentiate into the basic archaeocyte cell and then redifferentiate into a whole new type of cell. It"s part of how sponges respond to changes in their environment and the reason for their often asymmetric shapes: they can"t move, so they grow toward where they want to be.
