The vast majority of theses in this collection are open access and freely available. There are a small number of theses that have access restricted to the WWU campus. For off-campus access to a thesis labeled "Campus Only Access," please log in here with your WWU universal ID, or talk to your librarian about requesting the restricted thesis through interlibrary loan.
Date Permissions Signed
Date of Award
Master of Science (MS)
Bingham, Brian L., 1960-
Donovan, Deborah Anne, 1964-
Strom, Suzanne L., 1959-
The temperate sea anemone, Anthopleura elegantissima is facultatively symbiotic with at least two distinct algae: zooxanthellae (Symbiodinium muscatinei) and zoochlorellae (Elliptochloris marina). Symbiotic A. elegantissima potentially receive excess photosynthate from their algal partners, which supplements heterotrophic feeding. But asymbiotic individuals must rely solely on heterotrophic food sources. We predicted that asymbiotic A. elegantissima, due to their lack of algal symbionts, would have a more effective heterotrophic feeding strategy. Symbiotic and asymbiotic A. elegantissima were collected from the field and heterotrophic feeding features were measured (i.e., anemone morphology, tentacle adhesive force, nematocyte sensitivity, cnida size, cnida density, ingestion time, digestion time and absorption efficiency). The anemones were then exposed to natural sunlight or shaded conditions for three weeks and the feeding features were again compared. Few aspects of heterotrophic feeding in A. elegantissima were affected by symbiotic state. Asymbiotic anemones had the largest nematocysts immediately after collection, but were not more efficient predators. We found the greatest nematocyte sensitivity in anemones hosting zooxanthellae, suggesting a greater nutritional need for anemones in this symbiotic state. Though sunlight appeared to increase digestion rate in all anemones, irradiance also had negative effects. Anemones exposed to sunlight had lower cnida densities and smaller spirocysts. Sunlight also appeared to reduce cnidocyte function in asymbiotic individuals. Our results show that symbiotic state has little effect on heterotrophic feeding in A. elegantissima, suggesting that the symbiotic algae may contribute little to the host anemones' daily nutritional requirement and that nutrition in A. elegantissima may be obtained primarily through heterotrophy.
Western Washington University
Copying of this thesis in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Hiebert, Terra C. (Terra Celeste), "The effects of symbiotic state on heterotrophic feeding in the temperate anemone Anthopleura elegantissima" (2011). WWU Masters Thesis Collection. 143.