Thesis

The distribution of Cristispira in intertidal bivalve mollusks of the Pacific coast of Southern California

Over 1,000 bivalve mollusks, representing eighteen genera and twenty-two species, were collected in four years from twenty geographical sites from Santa Barbara, California to San Diego, California, and their crystalline styles were examined for bacteria. The giant spirochete, cristispira, was widely distributed among bivalves from all types of habitats, open and protected sandy beaches, rocky shores and estuaries, regardless of the season. In any one habitat, certain species never harbored Cristispira. The occurrence of Cristispira was neither correlated with the taxonomy of the bivalves, nor with the types of crystalline styles. The incidence of Cristispira was greater in small than in large specimens of Tivela Stultorum. Most bivalves were maintained successfully in sea water tanks and continued to possess crystalline styles, but certain bivalve species lost Cristispira during captivity. Small Spirochetes were often present in crystalline styles, while rod-shaped bacteria were rarely seen.

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