Triploblastic is a condition of the ovum in which there are
three primary germinal layers : the ectoderm, mesoderm, and
endoderm. Additionally, the term may refer to any ovum in which
the blastoderm splits into three layers. In higher and
intermediate animals, all organisms arise from a triploblastic
ovum. Triploblastic organisms are organisms which evolve from
such an ovum. Unlike diploblastic animals, in which cells are
proximate to the organism's environment, triploblastic animals
have internal cells that are not adjacent to external food
sources. Since all cells must be fed and waste removed, these
tasks are handled by various organs and circulatory and
digestive systems in any triploblastic animal. Compare to
diploblastic.