Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun The flat, free-swimming, ciliated larva of a cnidarian.
from The Century Dictionary.
- noun The ordinary locomotory embryo of the cœlenterates, which is of flattened form, mouthless, ciliate, and free-swimming.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Biol.) In embryonic development, a vesicle filled with fluid, formed from the morula by the divergence of its cells in such a manner as to give rise to a central space, around which the cells arrange themselves as an envelope; an embryonic form intermediate between the morula and gastrula. Sometimes used as synonymous with
gastrula . - noun (Zoöl.) The very young, free-swimming larva of the cœlenterates. It usually has a flattened oval or oblong form, and is entirely covered with cilia.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun biology In
embryonic development , avesicle filled withfluid , formed from themorula by thedivergence of itscells in such a manner as to give rise to a central space, around which the cells arrange themselves as anenvelope ; an embryonic form intermediate between the morula andgastrula . - noun zoology The
larva of ahydrozoan , which is free-swimming and covered incilia .
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun the flat ciliated free-swimming larva of hydrozoan coelenterates
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/Share-Alike License
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Examples
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Some said that the original embryonic form of the metazoa was not the gastrula, but the "planula" -- a double-walled vesicle with closed cavity and without mouth-aperture; the latter was supposed to pierce through gradually.
The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876
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After fertilization, the egg grows into a 'planula' (which is described above as a cilia covered larvae) then finds a spot to temporarily and finishes its last stage of life as a full grown
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He denied that the invagination opening (which he named the blastopore) represented the primitive mouth, [443] holding that this was typically formed by an "inruptive" process at the anterior end of the planula, which led to the formation of a "stomodæum."
Form and Function A Contribution to the History of Animal Morphology
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To the fourth stage he assigns the planæa, corresponding to the embryonic development of an albumen and the planula or ciliated {48} larva.
The Theories of Darwin and Their Relation to Philosophy, Religion, and Morality Rudolf Schmid
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It was afterwards shown that this planula (found in several sponges, etc.) was a later evolution from the gastrula.
The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876
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The Norwegian Magosphaera planula, swimming about by means of the lashes or cilia at its surface.
The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876
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Rhopalura Giardi (Julin): Figure 3 male, Figure 4 female, Figure 5 planula.
The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876
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Section of Magosphaera planula, showing how the pear-shaped cells in the centre of the gelatinous ball are connected by a fibrous process.
The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876
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The wall of the planula is next pushed in on one side, or invaginated, whereby it is converted into a double-walled sac with an opening, the _blastopore_, which leads into the cavity lined by the inner wall.
Darwiniana : Essays — Volume 02 Thomas Henry Huxley 1860
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Each expression pattern is represented by a red shading on the planula, polyp or medusa diagrams.
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