ASPECTS OF DEVELOPMENT AND OCCURRENCE OF CARCINONEMERTES EPIALTI (NEMERTEA) FROM SHORE CRABS IN MONTEREY BAY, CALIFORNIA

¹ Department of Biological Sciences, California State College, Stanislans, Turlock, California 95380

1. In the laboratory, females of Carcinonemertes epialti from Hemigrapsus oregonensis laid an average of 2.8 egg masses, one about every 2.4 days, for 12 days. Larvae started hatching in 6.6 days and lived an average of 21 days and a maximum of 50 days without metamorphosis.

2. Females of C. epialti from Pachygrapsus crassipes laid an average of 3.5 egg masses, one every 2.1 days, for 13 days. Larvae started hatching in 9 days. It took an average of 12.8 days for all larvae to emerge from egg masses. Larvae lived an average of 28 days without metamorphosis.

3. Egg masses were an average of 3.03 mm long and contained an average of 81 eggs per mass.

4. Adult worms lived about 22 days without food after egg laying ceased. Medium-sized starving worms lived about 73 days and starving juveniles lived 35 days in comparison.

5. In nature, 72.21% of the H. oregonensis population was infected, with an average of 14.56 worms/crab; 47.47% of the P. crassipes population was infected, with an average of 3.34 worms/crab.

6. In both crab populations brooding females were most heavily infected both in per cent infected and in average worm burden. These were followed by males, then nonbrooding females.

7. About 29% of the worms found on brooding H. oregonensis and about 27% of those found on brooding P. crassipes females were adult females. Peaks in abundance of adult female worms occurred in August-September and early Spring.

8. Worms were distributed primarily under the abdomen close to eggs of brooding female crabs. More worms were found at this location than at other sites on nonbrooding females; on males, worms were fairly evenly distributed in the axils between legs and on the abdomen.