Reproduction in Anthoplema — Ford 
141 
The most important fact realized from the 
data in Table 1 is that in no case were both an 
identifiable male and an identifiable female 
found in the same sample of 10 animals. In 
fact, in 25% of the samples, every individual 
was identified as a female. Assuming a random 
distribution of males and females, the prob- 
ability of a single sample of 10 animals being 
all of one sex is Vi to the 10th power, and of 
5 samples of 10 being all of one sex is Vl to 
the 50th power. Thus it is apparent that the 
sexes are not randomly distributed, but aggre- 
gated into separate or perhaps contiguous groups 
of males and females. 
What is not evident from the data presented 
is the size of the unisexual aggregations, as they 
were not sampled randomly but in patches about 
8 to 12 cm across. What is needed to estimate 
the size of the unisexual aggregations and even 
to show whether all continuous masses of ane- 
mones are of but one sex, is a series of random 
samples of say, 10 animals each, from a number 
of continuous aggregations. It should be noted 
that the 3 pairs of samples taken from con- 
tinuous masses (on rocks 6, 9, and 12) yielded 
but one sex in each case, and that in the 2 
cases in which both sexes were found on the 
same rock ( Nos. 1 and 3 ) , the pairs of samples 
were taken from separate aggregations. 
To estimate the sex ratio, there are two ways 
to manipulate the data in Table 1. If the data 
are considered to comprise a sample of 240 
individuals, the sex ratio is 102 identifiable as 
females to 38 males, or about 2.7:1, which for 
this sample size (140), deviates very significantly 
from a 1: 1 ratio. However, if each group of 10 
animals is considered to be a part of a separate 
asexually produced clone, and is treated as but 
a single individual, the sex ratio of identifiable 
animals is 15 females to 7 males, which for this 
sample size (22) does not deviate significantly 
from a 1 : 1 ratio, and suggests a need for sam- 
pling a larger number of aggregations, perhaps 
at other locations. 
Thus the clumped distribution of the sexes, 
and the apparent predominance of females in 
the population, explain in part the sex ratios 
observed in samples of animals collected in 1959 
and I960 for the study of the gonad cycle. The 
marked increase in the frequency of males ob- 
served in I960 over 1959 (indicated in Fig. 3) 
might well be explained by the unfortunate fact 
that the same rocks were not sampled in both 
years. Until mid-July, 1959, animals were taken 
from rocks in the area of rocks 1 through 6 of 
Table 1, which are in the northern half of the 
collecting area and adjacent to a small sandy 
beach to the north. In July, 1959, the sand level 
rose to cover most of the rocks from which 
animals had been collected. It should be noted 
that samples from rocks 1 through 6 consisted 
of mostly females and but a few males. Animals 
taken during the remainder of 1959 were taken 
in the area of rocks 5 through 9, samples from 
which yielded only females. The sand level did 
not rise to cover the anemones in the southern 
half of the collecting area, so in I960 animals 
were collected from the area of rocks 6 through 
12, from which a much larger proportion of 
males were taken. Thus the unfortunate cir- 
cumstances of sampling from a population in 
which the sexes are not randomly distributed are 
offered as the most probable explanation for the 
dearth of males in 1959 collections, and their 
sporadic occurrence in I960. 
It is interesting to speculate about the sig- 
nificance of the clumped distribution of the 
sexes with regard to the origin of the aggrega- 
tions in the population. It could be argued that, 
as is suggested above, unisexual aggregations 
are actually asexually produced clones, arising 
by binary fission from a single individual. In 
fact, throughout the year a few scattered indi- 
viduals are observed to be pulling apart in the 
process of fission, and there are usually a few 
individuals in each sample collected showing a 
light-colored vertical scar on the column indi- 
cating a recent division. Hand (1955) and 
others ( personal communication ) have reported 
seeing populations of A. elegantissima in which 
almost every anemone is dividing or has just 
divided, during the months of January to March. 
One might also suggest that the animals are 
in unisexual aggregations as the result of an 
active process of movement of individuals. How- 
ever, when a solidly packed aggregation is re- 
moved from the substrate except for a small 
patch of individuals in the center, and the patch 
is observed over a period of weeks, the tendency 
is for the animals to quickly spread out, separat- 
ing most of the individuals. Also, animals placed 
closely together in tanks in the laboratory sepa- 
