Long and Van Sant: Embryo development in golden king crab ( Lithodes aequispinus ) 
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Time (days) 
Figure 5 
Average (A) eye area and (B) maximum and minimum eye di- 
ameters for all embryos measured during each 20-day incre- 
ment during embryo development of golden king crab ( Lithodes 
aequispinus) . In section B, the line without points represents 
the ratio between the maximum and minimum eye diameters 
as an indicator of eye shape. Error bars indicate ±1 standard 
deviation of the mean. 
smaller numbers corresponded to more mature embryos 
(Table 2, Fig. 6). The second PC was negatively correlat- 
ed with egg size and yolk area and explained variation 
in egg sizes within a given stage (Table 2, Fig. 6). There 
were significant differences in embryo morphometries 
among females (ANOSIM: global _R=0.229, PcO.OOl) and 
stages (ANOSIM: global P=0.730, PcO.OOl). Although it 
is significant, the low value for the global R statistic 
indicates that, although there were statistical differ- 
ences among the females the differences were prob- 
ably negligible (Clarke and Warwick, 2001). Ordination 
by both PCA and nonmetric multidimensional scaling 
confirmed this conclusion. Pairwise comparisons of the 
stages showed that, in general, stages 0-5 could not be 
distinguished from each other (i.e., P> 0.050 or global 
P<0.200 and usually both) and that stages 6-12 each 
differed significantly from all other stages (in all cases 
PcO.OOl and global P>0.300). These results confirmed 
the results from PCA (see the PCA plot, Fig. 6). 
Discussion 
Embryo development in golden king crab exam- 
ined in this study was similar to that reported 
in other studies for the red king crab (Nakani- 
shi, 1987), blue king crab (Stevens, 2006), and 
snow crab (Moriyasu and Lanteigne, 1998). Most 
of the stages described in our study match close- 
ly stages identified in those other studies. This 
similarity is not surprising, especially for the 
similarities noted among the 3 closely related 
species of king crabs. Despite the general simi- 
larity, there were some aspects of embryogenesis 
in golden king crab that were distinct, such as 
the lack of a diapause and the rate of decrease 
in yolk area. 
Blue king crab undergo a diapause stage that 
lasts for approximately 2 months (Stevens, 2006) 
between the stages of chromatophore formation 
and eye enlargement (approximately equivalent 
to our stages 9 and 10). Snow crab undergo a 
6-month diapause once they reach the gastrula 
stage and a second diapause of 3-4 months after 
the eye pigment formation stage (approximately 
equivalent to our stage 8) in the field (Moriyasu 
and Lanteigne, 1998). Tanner crab ( Chionoecetes 
bairdi) also undergo a diapause of 3-6 months 
after the gastrula stage (Swiney, 2008). In snow 
crab, the diapauses seem to be the mechanism 
for switching between a 1-year and 2-year brood- 
ing period (Moriyasu and Lanteigne, 1998; Webb 
et ah, 2007), and, in both snow crab and Tan- 
ner crab, the purpose of varying the duration of 
embryonic development is likely to ensure that 
larval release coincides with the spring plank- 
tonic bloom (Swiney, 2008). It is probable that 
the golden king crab lacks a diapause stage be- 
cause its larval development is lecithotrophic. 
Lecithotrophic larvae do not need to feed, and 
golden king crab larvae do not appear to feed at 
all (Shirley and Zhou, 1997); therefore, there is 
no need to synchronize the release of larvae with food 
availability and, thus, there is no advantage to having 
a diapause stage. This interpretation matches with the 
observation of an asynchronous reproductive cycle for 
this species (Somerton and Otto, 1986). 
Another major, and expected, difference in golden 
king crab embryogenesis, compared with that of other 
crab species, is the rate at which the yolk area de- 
creases, and the amount of yolk remaining at hatching. 
The percent area of yolk decreases at a much faster 
rate in blue king crab than it does in golden king crab, 
and at the beginning of hatching blue king crab have 
only about 13% area of yolk (Stevens, 2006). Snow crab 
embryos have, at most, a trace of yolk left at hatch- 
ing (Moriyasu and Lanteigne, 1998), as do Tanner crab 
(Swiney et al., in press). In this study, golden king crab 
had more than 40% area of yolk remaining at hatching. 
Again, however, this difference is driven by the require- 
ments of lecithotrophic larval development; the larvae 
