Also found in: Medical, Encyclopedia, Wikipedia.


Having body tissues derived from only two germ layers, the endoderm and the ectoderm, as in the cnidarians.

dip′lo·blas′ty n.


(Biology) (of jellyfish, corals, and other coelenterates) having a body developed from only two germ layers (ectoderm and endoderm). Compare triploblastic


(ˌdɪp ləˈblæs tɪk)

having two embryological germ layers, the ectoderm and endoderm, as in cnidarians.
References in periodicals archive ?
The diploblastic cnidarian body plan comprising the epidermis and gastrodermis has remained largely unchanged since it evolved roughly 600 Ma.
However, we do appreciate that some of our standard marine invertebrate phyla are evidenced during the late Precambrian: sponges early on, then diploblastic organisms such as ctenophores and cnidarians, and later, early molluscs, flatworms, and possibly arthropods.
Despite being trained in comparative anatomy, or perhaps because of it, I was distrustful of some of the morphological criteria - for example, diploblastic versus triploblastic, or proterostome versus deuterostome - used in reconstructing phylogeny.
Commonly, cnidaria are considered diploblastic animals, with a cellular ectoderm and endoderm (gastroderm) separated by an acellular mesoglea (Brusca and Brusca, 2003).
Whether the cleavages are spiral or not, a major aspect of the evolution of diploblastic into triploblastic Metazoa is the formation of a third germ layer, the mesoderm.
WNT signalling molecules act in axis formation in the diploblastic metazoan Hydra.