An Analysis of Placozoan Nutrition and Biomineralization
An Analysis of Placozoan Nutrition and Biomineralization
Date
2006
Authors
Hassett, Whitney
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Gaidos, Eric
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Oceanography
Global Environmental Science
Global Environmental Science
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Abstract
Trichoplex adhaerens, the only species in the phylum Placozoa, is the simplest
and most primitive of all metazoans. Placozoans are found in the littoral zone of subtropical and tropical oceans, have a plate-like appearance and generally adhere to
surfaces. These extremely simple organisms have no organs, muscular system or
nervous system. Little information is known about their diet or behavior in the natural
environment. In the laboratory placozoans feed via phagocytosis on algae, living
protozoa, and detritus, and have been cultured using generic filter feeder food.
Experiments were performed in order to compare the success of populations of
placozoan strains who were fed a filter feeder medium versus a brine shrimp medium.
Placing a single placozoan in a petri dish and allowing it to reproduce asexually in
order to clone the organism resulted in different strains. There appeared to be no
preference for either media shown between the strains. A significant distinction that
was observed between strains was the presence of birefringent granules that exist in a
ring around the perimeter of the animal. Optical analysis, combustion experiments,
triammonium hydroxide tests, Scanning Electron Microscopy (SEM) and Raman
spectroscopy analyses were performed in order to discover the structure and
composition of the birefringent granules. Only certain strains were found to contain
birefringent granules that remained present over multiple generations, which could
imply there might be more than one species of Placozoa. The crystals were found to be
inorganic by combustion. Birefringence interference tests indicate that it is improbable
that the crystals are of calcium carbonate nature. SEM analysis uncovered crystals that
likely originated from the organism that indicate the presence of calcium and oxygen.
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biological oceanography
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37 pages
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