18 
PACIFIC SCIENCE, VoL XVIII, January 1964 
COPULATION : Many records of copulation in 
L. bellus bellus were obtained in the laboratory 
but none were obtained in the field. The season 
of copulation is just prior to egg deposition. 
This would suggest that only a brief period of 
a few days or weeks separates copulation and 
egg deposition. On June 9, seven females were 
dissected which had just hatched their first 
brood. Six showed ovaries in a highly developed 
and ovigerous condition, while one had ovaries 
showing no development. Of the seven, four 
had the spermatheca completely empty while 
two had a small amount of sperm present, and 
one had a large quantity of sperm. These data 
suggest that copulation is necessary prior to the 
second brood. The process of copulation in this 
subspecies is identical with that of L. bellus 
diegensis as described by Knudsen ( 1960:7). 
PRODUCTIVITY: The eggs in egg masses taken 
from 20 females of various size classes were 
counted and the average was determined. The 
number of eggs per brood ranged from 36,000 
down to 6,000, with an average for the 20 ani- 
mals of 15,640. Thus, an average for all females 
having two broods in a year could be 31,000 
eggs per year, but with only about 90% of the 
females producing a first brood and only about 
70% producing a second brood, a more accu- 
rate average for all females with or without eggs 
would be about 25,000 eggs per year. The av- 
erage egg count given here is extremely high 
as compared with L, leucomanus leucomanus 
(Knudsen, 1960:9) but the size range of the 
northern L. b. bellus is much larger than in 
those specimens counted for L. 1. leucomanus. 
LARVAL DEVELOPMENT: The larval develop- 
ment of L. bellus was studied and fully illus- 
trated and described by Hart (1935: 414-420). 
Since that time Menzies (1946:1-45) made a 
revision of the genus Lophopanopeus and has 
placed L. diegensis Rathbun in the L. bellus com- 
plex, making bellus and diegensis subspecies of 
the species bellus. After Menzies’ revision, the 
larval development of L. bellus diegensis was 
described by Knudsen (1959:57-64) and the 
larval development of L. leucomanus leucomanus 
was also studied (Knudsen, 1958:51-59). 
POSSIBLE TRIGGER MECHANISMS: The early 
part of the visible life cycle of this species is 
similar to that of Hemigrapsus nudus in that 
copulation occurs during and after the shortest 
days of the year and egg deposition begins about 
the same time as in H. nudus and continues as 
the photo-period lengthens. When daylight has 
reached its maximum length in June the second 
brood (which is lacking in H. nudus) begins 
and continues to follow the rise in water tem- 
perature. While there seems to be some corre- 
lation between photo-period, temperature, and 
the timing of brood number one and brood 
number two, data to support such correlations 
are lacking. 
family CANCRIDAE 
Cancer oregonensis 
HABITAT: Of the Puget Sound cancroid crabs, 
Cancer oregonensis is somewhat unique in that 
not all of the individuals migrate during the 
reproductive season, but rather many remain in 
a consistent area within the overall habitat. 
This species is consistently found with Lopho- 
panopeus bellus bellus and slightly above the 
latter species within the intertidal zone. The 
habitat requirements seem to be almost identi- 
cal with those of Lophopanopeus. It is also 
common to find this species high up on pilings 
which are heavily encrusted with barnacles and 
mussels. In this situation C. oregonensis selects 
a small cavity between the encrusting organisms 
and uses this for its home site. It feeds on 
barnacles and other marine organisms within 
and around this home site. 
FEEDING HABITS: While a large number of 
C. oregonensis stomachs were dissected during 
the routine of counting eggs and measuring 
ovary development, only a few animals had food 
within the stomachs. The rest, apparently, were 
not feeding during periods of reproductive ac- 
tivity. Prasad and Tampi (1951:675) report 
that females of the cancroid crab Neptunus 
pelagicus do not eat while carrying eggs on the 
pleopods, as is suggested here. The gut contents 
of eight individuals, five females and three 
males, were analyzed. In some, partially digested 
material resembling polychaete worms with nu- 
merous bristles was found. In others, fragments 
of Crustacea such as amphypods, small shrimp, 
or crabs were found. One animal had the stom- 
ach completely filled with red eggs identical to 
those carried on her own pleopods. There is 
little doubt but that this crab had been eating 
