PP - Protostome and Deuterostomes

The kingdom of animalia may be seperated into protostomes and deuterostomes. Protostomes includes animals such as annelids, molluscs, and insects, while deuterostomes includes organisms such as the echinoderms, hemichordates, chordaes and verebrates. There are 5 main characteristics which separate the protostomes and deuterostomes. During protostome development, the first opening to appear in the blastopore becomes the mouth of the organism. This pore deepens, eventually reaching through the organism, forming the gut and exiting at the anus. In contrast, during deuterostome development, the anus will form first, followed by the mouth. Protostomes cell layers develop slightly offset from one and other. This produces a spiral cleavage pattern. This is unlike deuterostome development, which has a radial cleavage, where the cells are stacked on top of each other. Furthermore cell role is determined very early on in protostome development, while deuterostome cell role is indeterminate. Lastly, the method of coelom development differs between protostome and deterostomes. Protostome coelom development proceeds through a process called schizocoely. During this method masses of the mesoderm migrate and form the coelom. However, deuterostomes perform enterocoely, where the mesoderm folds and pinches off to form the coelom.