The distribution and abundance of the interstitial acoel turbellarian, Diatomovora amoena Kozloff, 1965 was studied in an estuarine intertidal sand flat in Yaquina Bay, Oregon, from May 1970 through May 1971. Monthly measurements of biological (organics, sulfides, chlorophyll, and carotenoids), pore water (salinity, pH,oxygen, and temperature), and sediment (fine sediment percentage, grain size, sorting, skewness, and kurtosis) factors were made along a transect at four intertidal stations with elevations of -2.0, 0.0, 1. 6, and 3.0 feet, stratified by selection from a curve for tidal exposure, and at two depths (0, 0 cm to 0. 5 cm and 0. 5 cm to 1. 0 cm) of the sediment. Estuarine factors that were monitored continuously included temperature, salinity, tide elevation, and insolation. The interrelationships among these environmental parameters, their roles in the interstitial sediment system, and the hydrology of the groundwater in the beach, were investigated in order to characterize the interstitial environment of the sand flat and to determine the environmental factors limiting the distribution and abundance of D. amoena. Seasonality was indicated in most of the factors measured. The sediment system was strongly reducing during summer and fall as organic production increased. Particle size analyses showed that transport and deposition of fine sediments contributed to the development of reducing conditions. The properties of the interstitial environment of D. amoena were found to be controlled by the level of groundwater, rate of percolation, and degree of mixing within the beach. Density of D. amoena was highest during the fall and early winter, and lowest throughout the winter. Summer production of plant material in the lower intertidal lead to reducing conditions at the sediment surface. Reduction in animal density at the lower two stations was attributed to these reducing conditions, and to the rafting of animals away from the intertidal with the algal mat. Decrease in animal density in the upper two stations was attributed to lethal low temperatures and salinities that occurred during heavy precipitation in the winter and coincided with low tidal exposure. Exclusion of animals from depths greater than 0. 5 cm in the sediment was attributed to lethal levels of sulfide. Tolerance of D. amoena to temperature, salinity, and sulfide was determined experimentally. The 25 combinations of temperature and salinity, and the 12 combinations of temperature and sulfide that were employed were selected on the basis of actual levels measured in the study area. The temperature and salinity survival results were fitted to a response surface which was used to evaluate these factors in limiting animal distribution. Survival of acoels was independent of temperature up to 6 hours of exposure, and strongly temperature-dependent after 24 hours of exposure. Initial mortality was attributed to osmotic stress. Upon exposure to sulfide at 50 μgm S/ml, these animals did not survive beyond 6 hours, demonstrating that sulfide in high concentrations is toxic to D. amoena. At lower concentrations of sulfide (10 μgm S/ml), the acoels were able to live for over 20 hours. Lowering the temperature at both concentrations helped to prolong the lives of the animals. Levels of sulfide similar to those used in the experiment Levels of sulfide similar to those used in the experiment (10 μgm S/0.5 cm³ = 50 μgm S/ml.) were found at the sediment surface in the lower two stations during September, at which time animal density was found to be decreasing. At the upper two stations in September, where the level of sulfide was 3 μgm S/0.5 cm³, the acoel population was found to be increasing, thus bearing out the assumption that population density is, indeed, affected by sulfide. The nature of the interstitial sediment system as a habitat for meiofaunal organisms was explored and the role of the groundwater hydrology, as a buffer against seasonal variation in the estuary, in maintaining this system was examined. A portion of the littoral shore considered in this investigation was conceptualized as a factor model, the principal parts of which were selected for study. The seasonal cycles of the major input factors were found to be relatively stable from year to year, while the timing of these cycles varied. The numerous positive and negative correlations that were found within and between the biological, pore water, and sediment groups of factors indicated the multiplicity of direct and indirect interactions and supported the contention that the tidal flat is a complex interrelated system. Change in one or more of the major factors, such as precipitation, river runoff, sedimentation, or tidal prism, can be expected to have diverse effects on the littoral sediment environment. / Graduation date: 1972

From Resumé: The general picture of the physiology of invertebrate neuro-muscular systems as contrasted with the classical vertebrate system is presented and it is clear that one of the groups least investigated is the Phylum Platyhelminthes. An examination of the properties of the myo-neural system of a platyhelminth should be of interest, not only in itself, but also because of a possible relationship with the coelenterates, whose neuro-muscular system has been fairly extensively investigated. The aim of the present work was to determine some of the properties of the myo-neural system of a platyhelminth, and more especially those which would make possible a comparison with the myo-neural systems of other invertebrate phyla, and most particularly with the coelenterates. A preparation consisting of an entire decerebrate animal was used. The general anatomy of the musculature and basic plan of the nervous system are presented to facilitate an understanding of the experiments described, but a detailed examination of the relationships of nerves and muscles or of the innervation of the latter was not attempted. The spontaneous activity of such preparations was recorded kymographically and the characteristics of this activity under 'normal' conditions are described, together with observations on the effects on the normal spontaneous activity of treatments with sea waters of different ionic composition and with a number of drugs. The responses of the preparation to controlled electrical stimulation are also reported. The results are analysed and compared with the results of similar investigations on other invertebrate preparations, in particular the Anthozoa, and an interpretation of these results in terms of platyhelminth-coelenterate relations is discussed.

Thesis (Ph. D.)--Johns Hopkins University. / Cover title. Includes bibliographical references.

Thesis (Ph. D.)--Johns Hopkins University. / Cover title. Includes bibliographical references.

Thesis (doctoral)--Rijksuniversiteit te Leiden, 1929. / "Stellingen": p. [117-119]. Includes bibliographical references (p. 109-116).

Este trabalho consiste em uma caracterização morfológica das espécies-tipo da maioria dos gêneros que compõem a subfamília Geoplaninae, e quatro espécies destinadas a servir como grupos externos (Pelmatoplanini, Anzoplanini, Caenoplanini, Bipaliinae). A estudo morfológico das espécies resultou em 69 caracteres morfológicos que foram inseridos em uma matriz de dados e preparados para análise filogenética. Quinze espécies adicionais de outros gêneros de Geoplaninae também foram incluídos na análise. Os resultados corroboram o monofiletismo da subfamília Geoplaninae. De acordo com a hipótese de Meixner, o clado formado pelos gêneros Enterosyringa e Xerapoa, que compartilha características morfológicas com espécies do grupo externo, é o grupo de irmãos de todas as demais espécies de Geoplaninae. Descobrimos que as características anatômicas do aparelho copulador, como a presença e o tipo de papila peniana mostraram possuir muitas reversões e não se mostraram filogeneticamente informativas. Caracteres do sistema muscular podem ser usados de forma mais efetiva para a definição de grupos taxonômicos dentro do Geoplaninae e como indicadores de suas relações evolutivas. Nenhum dos aspectos diagnóstico atuais de da Geoplaninae correspondeu a caracteres autopomórficos em nossa análise. Nossos resultados sugerem que vários gêneros de Geoplaninae representam grupos não naturais, i.e., Geoplana e Notogynaphallia, com alguns caracteres diagnósticos sendo homoplásicos. / This work consists of a morphological characterization of the type species of most of the genera that compose Geoplaninae, and four species intended to serve as outgroups (Pelmatoplanini, Anzoplanini, Caenoplanini, Bipaliinae). The morphological study of the species resulted in 69 morphological characters that were entered into a data matrix and prepared for phylogenetic analysis. Fifteen additional species from other Geoplaninae genera were also included in the analysis. The results corroborate the monophyletic status of the subfamily Geoplaninae. According with Meixner\'s hypothesis, the clade formed by Enterosyringa and Xerapoa species, sharing morphological characteristics with outgroup species, is the sister group of all other Geoplaninae species. We found that anatomical features of the copulatory apparatus, such as the presence and type of penis papilla showed many reversions and were not phylogenetically informative. Characters of the muscular system can be used much better for defining taxonomic groups within the Geoplaninae and as indicators of their evolutionary relationships. None of the present diagnostic features of the Geoplaninae formed autapomorphic characters in our analysis. Our results suggest that several genera of Geoplaninae represent unnatural groups, viz., Geoplana and Notogynaphallia, with some diagnostic characters being homoplasic.

Este trabalho consiste em uma caracterização morfológica das espécies-tipo da maioria dos gêneros que compõem a subfamília Geoplaninae, e quatro espécies destinadas a servir como grupos externos (Pelmatoplanini, Anzoplanini, Caenoplanini, Bipaliinae). A estudo morfológico das espécies resultou em 69 caracteres morfológicos que foram inseridos em uma matriz de dados e preparados para análise filogenética. Quinze espécies adicionais de outros gêneros de Geoplaninae também foram incluídos na análise. Os resultados corroboram o monofiletismo da subfamília Geoplaninae. De acordo com a hipótese de Meixner, o clado formado pelos gêneros Enterosyringa e Xerapoa, que compartilha características morfológicas com espécies do grupo externo, é o grupo de irmãos de todas as demais espécies de Geoplaninae. Descobrimos que as características anatômicas do aparelho copulador, como a presença e o tipo de papila peniana mostraram possuir muitas reversões e não se mostraram filogeneticamente informativas. Caracteres do sistema muscular podem ser usados de forma mais efetiva para a definição de grupos taxonômicos dentro do Geoplaninae e como indicadores de suas relações evolutivas. Nenhum dos aspectos diagnóstico atuais de da Geoplaninae correspondeu a caracteres autopomórficos em nossa análise. Nossos resultados sugerem que vários gêneros de Geoplaninae representam grupos não naturais, i.e., Geoplana e Notogynaphallia, com alguns caracteres diagnósticos sendo homoplásicos. / This work consists of a morphological characterization of the type species of most of the genera that compose Geoplaninae, and four species intended to serve as outgroups (Pelmatoplanini, Anzoplanini, Caenoplanini, Bipaliinae). The morphological study of the species resulted in 69 morphological characters that were entered into a data matrix and prepared for phylogenetic analysis. Fifteen additional species from other Geoplaninae genera were also included in the analysis. The results corroborate the monophyletic status of the subfamily Geoplaninae. According with Meixner\'s hypothesis, the clade formed by Enterosyringa and Xerapoa species, sharing morphological characteristics with outgroup species, is the sister group of all other Geoplaninae species. We found that anatomical features of the copulatory apparatus, such as the presence and type of penis papilla showed many reversions and were not phylogenetically informative. Characters of the muscular system can be used much better for defining taxonomic groups within the Geoplaninae and as indicators of their evolutionary relationships. None of the present diagnostic features of the Geoplaninae formed autapomorphic characters in our analysis. Our results suggest that several genera of Geoplaninae represent unnatural groups, viz., Geoplana and Notogynaphallia, with some diagnostic characters being homoplasic.

No description available.

Marine flatworms are important mobile predators on hard substrate, however little is known about their life history. I recorded seven species of flatworms in Botany Bay and described a new species of flatworm Imogine lateotentare sp. nov. It is distinguished from other species in the same genus by having small, transparent and inconspicuous tentacles and continuous bands of numerous frontal and cerebral eyes. This new flatworm species was found closely associated with the barnacle Balanus variegatus (Darwin, 1854) on which it fed. Marine flatworms provide elaborate parental care to their offspring but its significance has not been experimentally confirmed. I provided quantitative measurements of the significance of parental care behaviour in Echinoplana celerrima and Stylochus pygmaeus under controlled laboratory conditions. I also examined the changes in reproductive behaviour of E. celerrima and the hatching success of their eggs when exposed to three putative flatworm egg predators. Brooding behaviour of neither species of flatworm enhanced the hatching success of their eggs and exposure of E. celerrima to the potential egg predators did not affect the timing of hatching or hatching success of its eggs. However, E. celerrima spent more time guarding their eggs when exposed to the potential egg predators. Brooding may be an innate behaviour in marine flatworms but it is not essential to their reproductive success. Marine flatworms are closely associated with sessile organisms and these assemblages are common in bays and estuaries which are subject to anthropogenic inputs from various sources. Impacts of pollutants are known for many flatworm prey species but little is known about the effects on the flatworm themselves. I examined the influence of sublethal concentrations of copper ranging from 0 to 50 ??g L-1 on the predatory and reproductive behaviour of Stylochus pygmaeus. These worms were more sensitive to low levels of copper pollution than their barnacle preys. Response of flatworms to physical stimulation, number of egg batches laid and hatching success were greatly reduced at higher copper concentrations. In areas polluted by heavy metals, flatworm populations will be affected at lower concentrations than their barnacle prey and which may alter sessile invertebrate community structure.

Marine flatworms are important mobile predators on hard substrate, however little is known about their life history. I recorded seven species of flatworms in Botany Bay and described a new species of flatworm Imogine lateotentare sp. nov. It is distinguished from other species in the same genus by having small, transparent and inconspicuous tentacles and continuous bands of numerous frontal and cerebral eyes. This new flatworm species was found closely associated with the barnacle Balanus variegatus (Darwin, 1854) on which it fed. Marine flatworms provide elaborate parental care to their offspring but its significance has not been experimentally confirmed. I provided quantitative measurements of the significance of parental care behaviour in Echinoplana celerrima and Stylochus pygmaeus under controlled laboratory conditions. I also examined the changes in reproductive behaviour of E. celerrima and the hatching success of their eggs when exposed to three putative flatworm egg predators. Brooding behaviour of neither species of flatworm enhanced the hatching success of their eggs and exposure of E. celerrima to the potential egg predators did not affect the timing of hatching or hatching success of its eggs. However, E. celerrima spent more time guarding their eggs when exposed to the potential egg predators. Brooding may be an innate behaviour in marine flatworms but it is not essential to their reproductive success. Marine flatworms are closely associated with sessile organisms and these assemblages are common in bays and estuaries which are subject to anthropogenic inputs from various sources. Impacts of pollutants are known for many flatworm prey species but little is known about the effects on the flatworm themselves. I examined the influence of sublethal concentrations of copper ranging from 0 to 50 ??g L-1 on the predatory and reproductive behaviour of Stylochus pygmaeus. These worms were more sensitive to low levels of copper pollution than their barnacle preys. Response of flatworms to physical stimulation, number of egg batches laid and hatching success were greatly reduced at higher copper concentrations. In areas polluted by heavy metals, flatworm populations will be affected at lower concentrations than their barnacle prey and which may alter sessile invertebrate community structure.