FEEDING BEHAVIOR AND REPRODUCTIVE CYCLES IN PISASTER OCHRACEUS 1 KARL PERRY MAUZEY Department of Zoology, University of Washington, Seattle, Washington, and Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington A number of studies have shown the importance of the relation between energy intake and reproductive effort in higher organisms. Lack (1954) summarizes a mass of data indicating, especially for birds, the dominant role played by the availability of food in determining reproductive strategy. His major conclusion, based on different degrees of reproductive success and survival, implicates a complex interaction with the environment. Among invertebrates the influence of natural selection on reproductive patterns and processes is poorly understood. In the field, the dependence of gamete production on food has been shown for copepods ( Marshall and Orr, 1955), rotifers (Edmondson, 1965) and for a few other organisms. Lab-oratory work is more convincing but generally less applicable. Experimental studies on Daphnla (Richman, 1958), a rotifer (King, 1965), as well as any study showing a relationship between rate of population growth and food level, can be thought of as giving evidence concerning the general dependence of the reproductive perform-ance on the nutritional state of the population. Among marine macro-invertebrates, a number of studies have suggested such dependence, but ecological data on feeding have been lacking. For example, Farmanfarmaian, Giese, Boolootian and Bennett (1958) have indicated an inverse relationship between the size of the gonads and pyloric caeca of two carnivorous sea-stars, Pisaster ochraceus and P. brevispinus. Pearse (1965) suggested that different populations of a probably omnivorous Antarctic sea-star, Odontastcr validns, varied in reproductive activity according to local differences in primary production. Boolootian, Farmanfarmaian and Giese (1962) have demonstrated reciprocal relationships between genital and hepatic tissue in the abalones Haliotis cracherodli and H. ntfescens, as have Lawrence, Lawrence and Giese (1965) for the algivorous chiton, Katharina tunicata. Most of these authors have suggested that the digestive glands are used to stockpile nutrients during the months when feeding is most efficient. Later these storage products are transferred to the maturing gonads. The hypothesis that changes in hepatic tissues are correlated with feeding can be tested most feasibly in a carnivorous species. Qualitative and cuiantitative aspects of the nutrition of carnivores are usually easier to follow under natural conditions since direct observation of ingested prey is possible. The starfish, Pisaster ocJiraceus (hereinafter referred to as Pisaster unless another species is indicated), was chosen for this study for several reasons. Pisaster is usualy abundant in the rocky intertidal region of San Juan Island, 1 This paper is a condensed version of a thesis submitted to The University of Washington in partial fulfillment of the requirements for the degree of Master of Science. 127
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