THE PREZOEAL STAGE OF THE DUNGENESS CRAB, CANCER MAGISTER DANA

¹ Department of Fisheries, Oregon State University, Marine Science Center, Newport, Oregon 97365
² Department of Wildlife, Oregon State University, Marine Science Center, Newport, Oregon 97365

1. Ninety-four per cent of eggs of the Dungeness crab, Cancer magister, held in sea water at 10.5 or 17.5° C and at salinities of 10 to 32% hatched into prezoeae during a 36-hour observation period. The highest and lowest numbers of eggs hatched at salinities of 15 and 10, respectively. At a salinity of 32, the mean percentages of eggs that hatched at 10.5 and 17.5° C were 30 and 73%, respectively.

2. With increase of salinity, the percentages of prezoeae that molted to first-stage zoeae increased from 0% at 10 to 100% at 30 and 32.

3. With increase of salinity from 15 to 32, the mean duration of the prezoeal stage decreased from more than 60 minutes to 11 minutes.

4. The experimental results show that the occurrence of a free prezoeal stage of short duration is normal in the life history of C. magister. The possibility that this is true for other Brachyura is discussed.