Weight-specific oxygen consumption of midgut gland tissue of Hemigrapsus nudus has been investigated at three levels of salinity (35%, 75% and 125% sea water), two levels of experimental temperature (5°C and 20°C) and four acute (Warburg) temperatures (5°, 10°, 15° and 20°C) in all combinations for each season (summer and winter). Metabolic-temperature curves reveal that at standard baseline conditions where the animals are held 24 hr at their respective seasonal temperature and salinity, midgut gland respiration is highest at all acute temperatures in the summer animals. Acutely measured metabolic-temperature curves for midgut gland tissue show that winter animals acclimated to their opposite seasonal conditions of temperature and salinity for 10 days demonstrate the greatest degree of acclimation. The effect of experimental temperature is statistically and biologically significant. The highest respiration rate is at 5°C. Low temperature (5°C) may provide a greater thermal stress than a high temperature (20°C) resulting in a higher rate of oxygen consumption. Experimental temperature also influences the seasonal respiratory response of midgut gland tissue to salinity. In summer animals there is no correlation of midgut gland respiration to salinity at 5°C. There is a increase in respiration rate as the osmotic gradient between the blood and medium increases at the seasonal baseline temperature of 20°C. Winter animals held at the seasonal baseline temperature of 5°C demonstrate a "V-shaped" relationship to salinity with the lowest respiratory response in 75% sea water where the gradient between the blood and medium is minimal. Animals held at 20°C increase respiration with an increase in salinity. It is suggested that the metabolic activity of midgut gland from summer animals may be related to the maintenance of a osmotic gradient between the blood and medium or alternatively to the energy demands associated with new exoskeleton formation. The proposal is put forth that midgut gland respiration in winter animals may indicate osmotic work being done to maintain the osmotic gradient between the blood and medium. The production of a urine hypotonic to the blood may also assist winter animals in regulation of blood electrolytes. The regression coefficients of weight-specific oxygen consumption as a function of body weight were not significantly different from zero at the 0.01 probability level. / Science, Faculty of / Zoology, Department of / Graduate

A structural analysis of the compound eye of Hemigrapsus nudus expands the basis of functional analysis of decapod Crustacean eyes. Contradictory evidence for disintegration of rhabdomeric microvilli in the absence of light prompted observation of H. nudus eyes after 146 days in darkness. Eyes were fixed with formalin and glutaraldehyde and post fixed with osmium tetroxide for electron and light microscopy. Light- dark-adapted eyes were also observed with hot water fixation and paraffin embedment. The eye of H. nudus is typical of decapod Crustacean compound eyes. Corneagenous cells underlie the transparent cuticle cone cells secrete the composite crystalline cone which contacts the rhabdom proximally. The single fused rhabdom is composed of layers of microvilli from two groups of retinular cells. The layers are oriented at right angles to each other, and perpendicular to the optic axis of the ommatidium. A presumptive four-lobed eighth retinular cell makes up the distal end of the rhabdom. Distal, proximal and reflecting retinal pigments are located in the distal pigment cells, retinular cells and tapetal cells, respectively. Distal and proximal pigments surround the rhabdom during light-adaptation, and withdraw during dark-adaptation. Reflecting pigment is found above the basement membrane in light-adapted eyes and below it in dark-adapted eyes. The crystalline cone may change length during light- and dark-adaptation. Prolonged darkness does not cause disintegration of the rhabdomeric microvilli. H. nudus lives in conditions of dim illumination. The fused, layered rhabdom is an efficient mechanism of light absorption. Internal reflection within the rhabdom is enhanced by the palisade and further increases light absorption. Functional units exist within the ommatidium. Mutually perpendicular rhabdomeric layers suggest intraretinal polarized light perception. Eighth retinular cells may respond individually to light focused on the distal rhabdom by the dioptric apparatus in mosaic image formation.

Graduation date: 1967

xi, 91 leaves : ill. Typescript Thesis (M.S.)--University of Oregon Includes vita and abstract Bibliography: leaves 87-91 Another copy on microfilm is located in Archives University of Oregon theses, Dept. of Biology, M.S., 1982

Hemigrapsus oregonensis and Hemigrapsus nudus, two beach crabs common on the Pacific Coast of North America, show considerable variation in numbers, and species dominance from place to place. To determine why this should be so, a number of experiments were performed, and observations made to determine what are the morphological, and physiological differences between the two species, and how the crabs would be affected by the different physical conditions prevailing in different places. In general, it appeared that H. nudus could not tolerate muddiness of the substrate, while H. oregonensis tended to be eliminated from clean areas by predators. The abundance of the crabs appears to be correlated with the amount of cover available. / Science, Faculty of / Zoology, Department of / Graduate

viii, 61 leaves : ill. ; 28 cm Typescript. (Another copy on microfilm is located in Archives) Thesis (M.S.)--University of Oregon Includes vita and abstract Bibliography: leaves 57-61 University of Oregon theses, Dept. of Biology, M.S., 1980

xi, 153 leaves : ill. Typescript. (Another copy on microfilm is located in Archives) Thesis (PhD.) -- University of Oregon Includes vita and abstract Bibliography: leaves 145-153 University of Oregon theses, Dept. of Biology, Ph.D., 1981

The present study has attempted to investigate some of the more basic questions concerning the toxicity and accumulation of mercury in the purple shore crab, Hemigrapsus nudus. This rocky intertidal denizen is found in abundance along the entire Pacific coast of the United States from Sitka, Alaska, to the Gulf of California where it dominates the mid-tide pool region. Local specimens were collected just north of the Pacific Marine Stations, Dillon Beach, Marin County, California. The animal is hearty and can be kept in a state of good health for long periods of time in the laboratory with minimum care and negligible mortality. Most importantly, as a middle intertidal inhabitant, H. nudus would be among the first groups of organisms to feel the stress of environmental contamination from an industrial source located on the open coast. This, coupled with its wide distribution, indicates its possible use as an environmental monitor.