Thesis

Ecological aspects of feeding behavior of some tellinaceans (Mollusca: bivalvia)

The feeding behavior of five species of tellinaceans was studied in four locations in California, USA. The organisms were studied in areas where they occurred sympatrically with other tellinaceans and in other areas where no other tellinaceans were present., Random samples were taken to determine population densities. Shell sizes were measured to determine if there was any difference due to competition. Each population was examined to ascertain the type of feeding behavior. Feeding behavior was determined from the stomach contents and from the behavior of the inhalent siphon. It was observed that when closely related species occur in the same location they exploit different microhabitats. Some organisms use suspended material as their primary food source, while others ingest deposits. Macoma nasuta is a deposit feeder when not in competition with other tellinaceans, but fed on both deposits and suspended material when coexisting with other deposit feeding Tellinacea. There is not any significant change in the population denslty or shell size which can be attributed to differences in feeding behavior. Growth of tellinacean species was the same in different geographical locations.

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