202 
PACIFIC SCIENCE, Vol. II, July, 1948 
TABLE 9 
Summary of the Incubation Time, Size, and Gross Development of the Ova of Captive P . 
crassipes during June, 1940. (Mean Aquarium Water Temperature, 16.2° C) 
WIDTH 
(MM.) 
LENGTH 
(MM.) 
DAYS 
AFTER 
EXPULSION 
GROSS DESCRIPTION OF DEVELOPMENT 
285 
320 
0 
uniformly dark brown; many zygotes, others in 4-8-cell stage, all 
blastomeres large; no perivitelline membrane apparent 
286 
311 
3 
uniformly dark brown; blastomeres filling capsule; homogeneous; 
no perivitelline membrane apparent 
288 
310 
5 
uniformly dark brown; blastomeres smaller and more numerous; 
slight withdrawal of blastomeres from one section of the capsule 
reveals perivitelline space 
291 
314 
8 
uniformly dark brown; blastomeres very numerous; further asym¬ 
metry in blastomeric bulk reveals greater perivitelline space 
294 
316 
10 
uniformly dark brown; differentiation progressing; no pigment 
deposits present; blastomeres occupy about 0.6 of egg capsule 
298 
328 
13 
differentiation advanced; no pigment deposits; yolk cells in one part 
of cell mass only 
312 
351 
18 
highly differentiated; heart not beating 
320 
358 
20 
highly differentiated; heart beating; structures plainly visible; few 
ova on bottom of aquarium 
324 
368 
24 
29 
no ova hatched; heart beat stronger, irregular (approximately 82 
beats per minute) 
all ova on bottom of aquarium; many hatched 
highly variable and apparently had no rela¬ 
tionship to the degree of embryological devel¬ 
opment. 
Both captive and wild ovigerous females were 
noted to thrust the chelae into the egg mass 
frequently, and to move the ova about in a 
manner which resembled a preening behavior. 
When the chelae were inserted into the sponge, 
the abdomen oscillated violently. Frequently, 
material which appeared to be ova was con¬ 
veyed to the mouth. The writer believes that 
this preening or cleansing behavior is not asso¬ 
ciated with actual ingestion of the eggs, inas¬ 
much as they thickly covered the bottom of the 
aquaria subsequent to this activity. It is pos¬ 
sible that accidental plucking of the eggs resulted 
from attempts to remove foreign particles from 
the egg mass. Most of the ova observed on the 
bottoms of the aquaria after this cleansing 
activity had a short portion of the funicle 
attached, indicating that they had been severed 
from the setae. Frequently, broken setae with 
several attached ova were found. The severed 
eggs were invariably viable regardless of the 
developmental level. 
The behavior of wild, ovigerous females with 
respect to submersion proved somewhat un¬ 
usual and contrary to expectation. They fre¬ 
quently wandered up a rock surface and 
remained motionless in the direct sun for 
lengthy periods—1 hour and 15 minutes on one 
occasion, and 5 minutes less than that on an¬ 
other. Both these females were observed on 
the same day during which the air temperature 
was 72° F. It was further noted that in collec¬ 
tions, the proportion of females increased dur¬ 
ing the breeding season, a fact which indicates 
that the ovigerous condition does not necessi¬ 
tate a sequestered existence. It seems likely, 
therefore, that the embryos demand no more 
than a minimum of submersion; further, the 
proportionately greater number of berried 
females found on the rocks than in tide pools 
may be associated with some biological require¬ 
ment such as increased warmth to permit the 
maximum tempo of embryonic development. 
The expulsion of more than one batch of 
eggs a year has been recorded for several of 
the Brachyura (Churchill, 1918; Broekhuysen, 
1936, 1941). Although no direct evidence of a 
