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Title: Studies on the Phylactolaemata
Author: Mundy, S. P.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1980
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Conventional morphological taxonomy has failed to provide solutions to certain taxonomic confusions within the class Phylactolaemata. Electrophoresis has been used here to examine genetic variation between three pairs of nominate species at several enzyme loci. This work has established beyond doubt that Plumatella coralloides, P. emarginata, P. fungosa and P. repens are separate species, and that P. emarqinata is less closely related to the other three species than they are to each other. Morphological characters for the identification of the species are discussed and evaluated. A revised key to the British and European Phylactolaemata is presented, accompanied by notes on their general biology and details of sites where British species have been found. The stereoscan electron microscope has been used to examine external and internal features of statoblasts. Certain features of taxonomic importance are described. A method for the laboratory culture of Cristatella mucedo colonies is described, and the value of yeast suspensions and certain algae and protozoa as food is discussed. The technique was used to examine the effects of low copper concentrations on colony growth and on the fine structure of the lateral tentacle cells. C. mucedo was found to be more sensitive to low copper concentrations than most freshwater animals. Ultrastructural observations showed that copper concentrations of 5 μgl had a significant effect on the relative volume of mitochondria per cell, the surface area to volume ratio of cristae, the nuclear envelope and the endoplasmic reticulum. These effects were enhanced by increasing concentration or exposure time, and their significance is discussed. Experiments were performed on the viability of statoblasts of P. emarginata following prolonged exposure to a wide range of concentrations of cadmium, copper, iron, lead, mercury, arsenic and molybdenum. The statoblasts were found to be highly tolerant of such exposures, and possible mechanisms of statoblast tolerance to heavy metals are discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available