Ancestrula sentence example

ancestrula
  • The Polyzoa are colonial animals, the colony (zoarium) originating in most cases from a free-swimming larva, which attaches itself to some solid object and becomes metamorphosed into the primary individual, or "ancestrula."
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  • The ancestrula (After Allman.) inaugurates a process of budding, conFIG.
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  • As indications that the conditions described in Membranipora and Cribrilina are of special significance may be noted the fact that the ancestrula of many genera which have well-developed compensation-sacs in the rest of their zooecia is a Membranipora-like individual with a series of marginal calcareous spines, and the further fact that a considerable proportion of the Cretaceous Cheilostomes belong either to the Membraniporidae or to the Cribrilinidae.
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  • Fixation takes place by means of this sucker, which is everted for the purpose, part of its epithelium becoming the basal ectoderm of the ancestrula.
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  • Finally, in the Phylactolaemata, the larva becomes an ancestrula before it is hatched, and one or several polypides may be present when fixation is effected.
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  • As in the case of Cyphonautes, the larval organs degenerate and the larva becomes the ancestrula from which a polypide is developed as a bud.
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