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Biology

Portland State University

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Full-Text Articles in Life Sciences

Assessing Well-Being Of Asian Elephants (Elephas Maximus) Through Major Events And Transitions, With Development And Aging, And Husbandry Changes, Sharon Stuart Glaeser Jul 2020

Assessing Well-Being Of Asian Elephants (Elephas Maximus) Through Major Events And Transitions, With Development And Aging, And Husbandry Changes, Sharon Stuart Glaeser

Dissertations and Theses

In this body of research, reproductive and adrenal hormones and behavior were used to evaluate individual and group responses to physiological, social, and environmental changes in zoo-housed Asian elephants, considering factors of sex, age, and life stage. Animals experience physiological, social, and environmental changes as part of their natural history and individual life experience. Measures of both positive and negative states are needed to assess the impact of these changes at the individual and group level. Such measures can help us better understand how animals cope with a changing environment, and can help inform management decisions. Through longitudinal analyses of …


Localization Of Neurosecretory Cells Within The Cerebral Ganglia Of Amphiphorus Imparispinosus Griffin, 1898 (Hoplonemertea) And Their Possible Regulatory Role In The Annual Reproductive Cycle, Gail H. Jacobson Jan 1977

Localization Of Neurosecretory Cells Within The Cerebral Ganglia Of Amphiphorus Imparispinosus Griffin, 1898 (Hoplonemertea) And Their Possible Regulatory Role In The Annual Reproductive Cycle, Gail H. Jacobson

Dissertations and Theses

Nemerteans are common invertebrates along coastlines in both temperate and arctic climates throughout the world. Amphiphorus imparispinosus is a carnivorous member of this phylum that is found abundantly in the intertidal areas of the Oregon coast. As in many other invertebrate phyla, endocrine integration within the nemerteans is thought to be accomplished by neurosecretory mechanisms. In Amphiphorus the presence of these neurosecretory systems has not been previously shown. This project was undertaken to determine if neurosecretory cells are present within the central nervous system of this species and. further, to examine seasonal changes in the number and appearance of these …