0The three basic body plans of bilaterally symmetrical animals are acoelomates, wherein nobody cavity other than the digestive tract exists; pseudocoelomates, wherein there is a cavity between the mesoderm and the endoderm; and the coelomates, where there is a cavity completely bounded by mesoderm. The internal organs are suspended in coelom by mesodermal double layer mesenteries. In wormlike organisms are found acoelomate and pseudocoelomate body plans; in advance invertebrates and vertebrates only coelomate body plan is found.
