Term of Award

Summer 2007

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

Sophie B. George

Committee Member 1

Steve Vives

Committee Member 2

C. Ray Chandler

Abstract

Ingestion rates for five species of echinoderm larvae, the sea stars Dermasterias imbricata, Pisaster ochraceus, and Evasterias troschelii, the sea urchin Strongylocentrotus purpuratus, and the sand dollar Dendraster excentricus, were investigated by assigning larvae to three natural and one artificial diet in the laboratory. The natural algal diets included Dunaliella tertiolecta, Isochrysis galbana and Rhodomonas sp. The artificial diet used was a 10-fold diluted artificial feed made from the concentrate of Ziegler E-Z Larval diet. The numbers of cells ingested per minute and total body length were recorded for each species. The volume of cells ingested varied significantly among species, diets and larval age. Pisaster and Evasterias larvae ingested particles at similar and at significantly higher rates than Dermasterias larvae. All three species ingested significantly higher volumes of the larger alga Rhodomonas and the medium-sized alga Dunaliella than the artificial diet. Younger larvae ingested large and medium-sized particles at lower rates than older larvae. Ingestion rates decreased for larvae close to metamorphic competency. For sea urchin and sand dollar larvae, Dendraster larvae were more efficient at ingesting both the large and small particles and less efficient in ingesting the medium-sized particles compared to Strongylocentrotus larvae. Both larvae ingested the larger alga Rhodomonas at significantly higher rates than the artificial diet. Younger sea urchin larvae ingested significantly lower volumes of all of the diets compared to older larvae. The differences in ingestion rates of these five echinoderm species might be due to differences in size, form, density of cilia, length of the ciliated larval band, and differences in size and palatability of the various diets. This is the first study documenting sea star larvae ingesting artificial and natural particles. The use of an artificial diet instead of natural diets has great implications for both aquaculture and embryological studies in the medical field.

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