Usually the central zooid in a Siphonophore to which the other zooids are attached is not a bladder-like float, but is an upright tube of greater or less length.
Each of these parts is a peculiarly modified polyp- or medusa-zooid produced by budding from an original central zooid.
The balance of evidence is nevertheless in my opinion in favour of regarding the Siphonophora as compound stocks, and the views of Claus on this subject (Zoologie, p.
The protoplasmic layer of the ovum is represented in black.
In the median line of the protuberance a furrow appears (fig.
In Alcyonium palmatum the impregnation is external.
The epiblast is especially thickened at a pole, which may be called the oral pole, and towards the side of this, which will be spoken of as the ventral side.
Both are formed by a solid process of epiblast in which a cavity--the cavity of the nectocalyx or pneumatocyst--is eventually hollowed out.
This vesicle appears to be filled with sea-water, in which the ovum floats.
In all the Siphonophora, so far observed, the starting point for further development is a typical ciliated two-layered planula.
With reference to this subject the observations of Lacaze Duthiers are especially valuable and striking.
The invaginated tube would seem to give rise to the so-called stomach, while the chamber at its aboral extremity is no doubt the infundibulum, which as may be gathered from Kowalevsky's statements, is lined by a flattened epithelium.
It has however no communication with the enclosed cavity of the pneumatocyst.
It is to be presumed, though not stated, that by an absorption of the blind end of the stomodaeal invagination the gastric chamber is placed in free communication with the spaces between the mesenteries[81].
In the female zooid the eggs are carried into a kind of pouch where they undergo their development and give rise to asexual parent stocks.
In such instances it is necessary to suppose that the umbrella of the primitive zooid of the whole colony has become aborted.
The anterior asexual zooidcontinues to produce fresh sexual zooids by fission.
The primitive zooidof a Siphonophora stock is thus a Medusa.
A shoot or bud of a plant; a polyp or zooid of the compound Hydrozoa Anthozoa, etc.
The individuals are round and disk-shaped, with a large zooid in the center of the under side, surrounded by smaller nutritive and reproductive zooids, and by slender dactylozooids near the margin.
Each zooid buds from the one immediately preceding it in the series, and intercommunication is effected by all the budding orifices (including that in the wall of the sicula) remaining permanently open.
A Monograptus makes its first appearance as a minute dagger-like body (the sicula), which represents the flattened covering of the primary or embryonic zooid of the colony.
From this bud is developed the first zooid and first serial theca of the colony.
The two atrial tubes of each zooid remain separate in front but unite posteriorly.
The remainder of the alimentary tract of each zooid is formed as a bud from the hind end of the branchial sack in the usual way.
The alimentary tracts of the four Ascidiozooids are at first in free communication by tubes opening from the hinder extremity of one zooid into the dorsal side of the branchial sack of the next zooid.
The growth or development of an animal or a zooid from a nonsexual germ.
A hydrozoan reproductive zooid or gonophore which does not become medusoid in form or structure.
Defn: The growth or development of an animal or a zooidfrom a nonsexual germ.
Defn: A sexual zooidproduced as a medusoid bud upon a hydroid, sometimes becoming a free hydromedusa, sometimes remaining attached.
Defn: A zooid of the third generation in asexual reproduction.
An independent, or partially independent, zooid of a compound animal.
Defn: A shoot or bud of a plant; a polyp or zooid of the compound Hydrozoa Anthozoa, etc.
A zooid of the third generation in asexual reproduction.
A kind of zooid of Siphonophora which has an elongated or even vermiform body, with one tentacle, but no mouth.
A sexual zooid produced as a medusoid bud upon a hydroid, sometimes becoming a free hydromedusa, sometimes remaining attached.
Mr. Busk, however, does not know of any gradations now existing between a zooid and an avicularium.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "zooid" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: animal; being; creature; individual; microbe; microorganism; organism; organization; virus
