What Is the Gastraea Theory?

James H. Sterling
James H. Sterling
• • 6 min read

Haeckel's Studies of Development in Calcareous Sponges (1872) Led Him to Develop the "Gastraea Theory," Which Proposes That the Ancestral Mode of Germ Layer...

What Is the Gastraea Theory?

Haeckel's studies of development in calcareous sponges (1872) led him to develop the "Gastraea Theory," which proposes that the ancestral mode of germ layer

germ layer
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). ... The word ectoderm comes from the Greek ektos meaning "outside", and derma meaning "skin".
› wiki › Ectoderm
formation, or gastrulation, was by invagination
invagination
Invagination is the morphogenetic processes by which an embryo takes form, and is the initial step of gastrulation, the massive reorganization of the embryo from a simple spherical ball of cells, the blastula, into a multi-layered organism, with differentiated germ layers: endoderm, mesoderm, and ectoderm.
› wiki › Invagination
to produce a functional gut. ... raphanus in order to understand when gastrulation occurs.

What is the Gastrea theory?

The gastraea hypothesis was proposed by Ernst Haeckel, shortly after his work on the calcareous sponges. He proposed that this group of sponges is monophyletic with all eumetazoans, including the bilaterians. This suggested that the gastrulation and the gastrula stage are universal for eumetazoans.

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What is Haeckel's biogenetic law?

The biogenetic law is a theory of development and evolution proposed by Ernst Haeckel in Germany in the 1860s. ... The biogenetic law states that each embryo's developmental stage represents an adult form of an evolutionary ancestor.

James H. Sterling

James H. Sterling

Environmental Science & Climate Journalist
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James Sterling reports on renewable energy developments, climate policy, ecological conservation, and green tech innovations around the globe.