Calcium and Phosphorus Metabolism of P. vigil — Sather 
203 
Calcium and Phosphorus Contents of Five Or- 
gans Throughout the Molt Cycle 
The calcium and phosphorus contents of the 
carapace, gills, mid-gut gland, muscle, and 
blood were determined. The values, based on 
per cent dry weight, are plotted in Figures 4-8. 
The blood data are given in mM/liter. Inter- 
action analyses on the organs’ calcium and phos- 
phorus contents were positive (P < 0.01). 
The intermolt carapace calcium content (Fig. 
4) was 49.51% and the phosphorus con- 
tent was only 5.42%. Both of these values are 
large in comparison with those reported by 
Prenant (1928) for five species of crabs in 
temperate waters. His data (per cent calcium 
and phosphorus, respectively) were: Carcinus 
maenas, 30 and 2; Maia squinado, 31 and 2; 
Portunus puher, 36 and 2; Cancer pagurus, 
3 6 and 0.8; and Xantho floridus, 38 and 0.4. 
However, as noted by Vinogradov (1953), the 
majority of these values were only relative. 
Hayes, Singer, and Armstrong (1962) reported 
that the carapace calcium of the lobster, Ho ma- 
ms vulgaris, was 25.2% and the calcium con- 
tent of the claw was 23.8%. The phosphate 
contents of these two anatomical areas were 
reported to be 1.33% and 2.05%. The lower 
calcium content of temperate species may be a 
genetic difference or may be caused by a lesser 
availability of this environmental element. Un- 
fortunately, this latter possibility cannot be 
checked because calcium data at the collection 
sites were not available. The environmental 
calcium content certainly influences the amount 
absorbed by an organism, as well as the amount 
retained. It is known that the total calcium 
content of fresh water crustaceans is less than 
that in marine species. 
The calcium alterations of the carapace 
during the molt cycle are illustrated in Figure 
4. Preceding molt, the calcium content varied 
only slightly during the D periods. After 
ecdysis (A^) the calcium content was dimin- 
ished to 26.04% and reflected the amounts 
in the epicuticle and pigmented layers. Be- 
tween Bj.g and Q. 2 , which was the major 
duration of calcification, the calcium content 
was increased significantly to 41.12%, which 
was similar to that of intermolt. 
The phosphorus changes of the carapace are 
also illustrated in Figure 4. The content at 
C 3 . 4 was calculated to be 5.42%, which is much 
greater than that found in Panulirus argus by 
Travis (1957). In P. argus, in late stage C, 
about 3% of the total integument was com- 
posed of Ca 3 (P0 4 ) 2 , which is approximately 
O. 2% of the total phosphorus. In P. vigil, a 
small insignificant increase was observed during 
the last proecdysis stages. At stages A^, the 
phosphorus content was increased to 26.76% 
of the dry weight, which was about the same 
as the calcium concentration. This localization 
could have been due to the mobilization of 
phosphorus by the blood. Travis (1957) has 
demonstrated that the postecdysial integument 
stains heavily for alkaline phosphatase. Thus, 
a much greater amount of phosphorus would 
be present than during the other stages. It is 
thought that alkaline phosphatase liberates 
phosphates which combine with calcium to 
form the calcium phosphate complex. The high 
phosphate content during the A stages causes 
one to ponder over its significance, because the 
major anionic constituent of the intermolt in- 
tegument is carbonate and not phosphate. In 
P. vigil during the first C periods, the phos- 
phorus content decreased significantly to 
11.34%. This reduction can be attributed to 
the increased deposition of calcium salts. 
The fluctuations in gill calcium are plotted 
in Figure 5. No significant differences were 
found between the intermolt value of 7.88% 
and the first premolt values. However, the 
decreased value of 0.30% at B^ did differ 
significantly from the other values. Because the 
period is the initial duration of greatest 
calcification, a high gill permeability, caused by 
calcium, would be greatly detrimental for ex- 
traction of calcium from the medium. Robertson 
(I960) demonstrated that a great influx of 
calcium occurred during postmolt in Carcinus 
maenas. Unfortunately, the amount of calcium 
in the gills was not measured. It appears, then, 
that in P. vigil the mechanism to increase the 
movement of calcium into the animal serves to 
reduce the gill calcium content, allowing cal- 
cium to enter across the gills at a more rapid 
diffusion rate, the blood then mobilizing the 
element to the integument. 
The phosphorus content of the gills during 
the molt cycle is illustrated in Figure 5. The 
