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…showed last 75 words of 310 total…on type of symmetry, number of tissue layers, type of coelom, and presence of segmentation. The bottom half of the plylogenetic tree contains organisms that lack a true coelom such as the porifera, cnideria, platyhelminthes. The rotifera and nematoda are pseudocoelomates which are right above the acoelomates. Everything above are coelomates, wich are either protostomes or deuterostomes. This allow seperation of echinodermata and chordata, which are deutrostomes, and arthropods, mollusca, and annelida, which are protostomes.