PROTOSTOMIA
"Mouth First" Organisms
[© Beckmannjan]
Chapter Outline
- Description of Protostomia
- Classification of Protostomia
- Lophotrochozoa
- Annelida
- Mollusca
- Gnathifera
- Ecdysozoa
- Panarthropoda
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The name Protostomia, translated from the Greek, means roughly "mouth-first". This refers to the way the embryo develops. Almost all animals have embryos which go through a process called gastrulation early in their development. The initial ball of cells starts to develop a "dent" in it, resulting in a cup- or bowl-shaped mass of cells. The opening of the cup or bowl either becomes the organism's mouth or its anus. If it will become its mouth, it is a protostome. If it will become its anus, it is a deuterostome ("mouth second"), which will be explored in chapter 31.
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