Blastaea

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Blastaea

 

a hypothetical ancestor of multicellular animals.

In the opinion of E. Haeckel, the blastaea was a globular organism that had an interior cavity and a walled body and consisted of a single layer of cells. Haeckel believed that colonial protozoa (Volvox, for example) were analogues of the blastaea. Proceeding from the position he had developed, that the organism in its individual development (ontogeny) briefly repeats the history of the development of the species (phylogeny), Haeckel believed that one of the stages in the development of the embryos of all multicellular animals (the blastula) is a repetition of the structure of the blastaea in ontogeny.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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The newly advanced theory for the origin of the eumetazoans (Nielsen, 2008b) proposes that the ancestral eumetazoan which Haeckel (1874) called gastraea did not evolve directly from a blastaea, but from sexually mature larvae of a homoscleromorph-like sponge with a pelago-benthic life cycle.