ANNUAL REPRODUCTIVE CYCLES OF THE CHITONS, KATHERINA TUNICATA AND MOPALIA HINDSII x A. C. GIESE, J. S. TUCKER AND R. A. BOOLOOTIAN 2 Hopkins Marine Station of Stanford University, California The reproductive season of marine invertebrates has been determined in a variety of ways: spawning, the appearance of young in plankton, increase in size of gonad relative to the body, and development of ripe gametes (see Giese, 1959, for reference). In most cases an annual reproductive season has been observed, but many species breed more than once during the season, some showing a monthly rhythm (Korringa, 1947). Data on reproductive seasons of marine invertebrates are still not extensive and the problems posed are numerous. It is desirable that data on many more species be gathered to gain a better perspective. This paper records observations on reproduction in two species of chitons, Katherina tunicata, an intertidal form, and Mopalia hindsii, a pile dweller. METHODS Ten specimens of Katherina were gathered monthly from the mid-littoral zone' of Carmel Point during 1954-55 and from the same zone at Yankee Point during 1956-58, in each case from rocks in the Postelsia and mussel zone exposed at low tide. The specimens at Carmel Point were larger but the population was sparser, and perhaps less representative than that at Yankee Point. The sample from Yankee Point was therefore selective inasmuch as very small specimens were avoided (weights: 1957, 16-44 gms.; 1958, 11-53 gms.) Ten specimens of Mopalia were obtained during monthly low tides from the pilings at Monterey harbor. The population in this region is unusual in that the specimens are preponderantly large and not too numerous, therefore the samples may not be truly representative of the species (weights : 1957, 14-73 gms. ; 1958, 16-65 gms.). However, this species was not found in other accessible environments in sufficient numbers for sampling. Each chiton was weighed, the foot removed and the animal eviscerated, per-mitting easy removal of the gonad. The gonad volume was determined and the gonad index (the volume of the gonad is divided by the weight of the animal and multiplied by 100) determined. To determine whether any striking changes in the content of nutrients oc-curred in the blood during the course of the reproductive cycle of Katherina, the reducing sugar, protein and non-protein nitrogen were determined monthly in samples of blood. For this purpose the blood of from ten to twenty individuals 1 Supported in part by U.S.P.H. Grant 4578 to A. C. Giese. We are indebted to Mrs. M. Lusignan, Mr. G. Araki, Mr. J. Bennett, Mr. A. Farmanfarmaian, Dr. A. T. Giese and Mr. John Schmaelzle for cartographic, statistical and sampling help. 2 Now at the Department of Zoology, University of California at Los Angeles. 81
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