vi, 58 p. ; ill., maps. A print copy of this title is available from the Oregon Institute of Marine Biology library, under the call number OIMB QL391.A6 W5. / The tube hood orientation of Pista pacifica is non-random and related to current direction. Results from field measurements and from one flow tank experiment suggest that Pista pacifica build their tube hoods at right angles to local currents, and perhaps away from the direction of any sediment transport which may occur normal to the prevalent current direction. By orienting their tube hoods perpendicular to water currents, the animals may be making use of the kinetic energy of the water motion around them to generate a tube ventilation current. This current may in turn lessen the energetic needs of the worms by providing internal ventilation and sediment flushing currents at little energetic cost to the organism. / Adviser: Robert C. Terwilliger

Arginase has been found to occur in the tentacles, gut, and body wall of Pista pacifica Berkeley_ Partially purified arginase from the intestine has a molecular weight of 200,000, a Km of about 155 mM, an arginase/canavanase ratio of 22, a pH optimum of 10.5, and a temperature optimum of 60°C. In addition, P. pacifica arginase is competitively inhibited by ornithine but is not inhibited by high arginine concentrations, nor by sulfhydryl reagents. The enzyme is not stimulated by exogenous manganese and breaks down into an active subunit under harsh treatment. The subunit has a KID of about 118 mM and is also unaffected by exogenous manganese. Polychaete arginase shows most of the properties characteristic of arginases from other animal and plant species. However, none of the characteristics observed to date can be correlated with a particular mode of nitrotelism.