Planarians lack dedicated respiratory and circulatory systems. this deficiency does not cause a problem because planarians lack dedicated respiratory and circulatory systems. this deficiency does not cause a problem because they lack mesoderm as embryos and, therefore, lack the adult tissues derived from mesoderm their body cavity, a pseudocoelom, carries out these functions their flame bulbs can carry out respiratory and circulatory functions none of their cells are far removed from the gastrovascular cavity or from the external environment

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Planarians lack dedicated respiratory and circulatory systems. this deficiency does not cause a problem because planarians lack dedicated respiratory and circulatory systems. this deficiency does not cause a problem because they lack mesoderm as embryos and, therefore, lack the adult tissues derived from mesoderm their body cavity, a pseudocoelom, carries out these functions their flame bulbs can carry out respiratory and circulatory functions none of their cells are far removed from the gastrovascular cavity or from the external environment

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I think that the deficiency of the dedicated respiratory and circulatory systems in Planarians is not caused by the fact that none of their cells are removed far from the gastrointestinal cavity or the external environment. Planarians are living flatworms and form the class Turbellarians in the Phylum Platyhelminthes. Flatworms have three layers of tissue, namely the ectoderm, mesoderm, and endoderm.