Isopods in Shark Samples 



Cirolana borealis (129 total individuals) were 

 present only in shark samples 1-5 taken in 1978. 

 One individual of a different isopod species and 

 one copepod were also noted in the samples. Table 

 1 shows the C. borealis population composition for 

 each sample. No manca larvae or true juveniles 

 were found; all had completed the molt to seven 

 peraeonal appendages, although the last pair of 

 pereopods were small in some individuals in the 5 

 mm class. No ovigerous females or females with 

 remnant marsupia were seen. A morphological 

 distinction between isopods was noted in that 

 the pleopods of individuals from the conus and 

 ventricle were consistently swollen, while about 

 half of those from the pericardial chamber, and 

 only two of the isopods from the gills, showed this 

 condition. The distinction was present prior to 

 preservation of the samples, and was possibly an 

 osmotic response to the body fluids of the host. The 

 distribution of C. borealis in the same samples 

 pooled by site of occurrence is shown in Table 2 

 (note relationships between the groups, particu- 

 larly in the male to female ratios). 



Shark Pathology 



Intact isopods in the isolated shark samples 

 were observed free within the pericardial cham- 

 ber; others had their mouthparts attached to the 

 tissues of the atrium and ventricle. In two in- 

 stances (samples 1 and 3), a single, large female 

 was attached in the conus arteriosus, caudad- 

 directed, anterior to the proximal semilunar 

 valves. There was no sign of external entry into 

 the conus or aorta. Abrasions were evident on the 

 exterior of the ventricles, and holes extended into 

 the lumen; large isopods with guts distended and 

 dark from feeding were present in pockets of tissue 



Table 2. — Distribution of Cirolana borealis by morphological 

 site of occurrence in pooled Carcharhinus milherti samples isee 

 text) collected off the Florida Atlantic coast in 1978. 



in the ventricular walls (Figure 1). Areas of 

 possible necrosis were noted in these samples. 

 Much of the gill tissue was destroyed on the 

 branchial arches, exposing the cartilaginous gill 

 rays. The epidermal section was abraded. 



Two free isopods were in the pericardial cham- 

 ber of the intact shark (sample 5). A small hole 

 (chewed) through the coracobranchial muscula- 

 ture led into the chamber from the left posterior- 

 most gill. No isopods were present in the interior 

 of the ventricle, conus, or circulatory system. The 

 tranverse septum was entire (as was that of 

 sample 3). Two isopods were attached at the 

 cloacal opening, and both claspers showed minor 

 surface injury. The hide was deeply pitted at the 

 axil of the pectoral fins and the soft areas at the 

 median fin bases. 



Histopathology of the Shark Heart 



Histopathological examination of heart sample 

 1 showed several C. borealis in the atrium near the 

 atrioventricular opening; the adjacent endocar- 

 dium and myocardium surrounding one of the 

 organisms had areas of necrosis, determined by 

 observation of basophilic degeneration of myo- 

 cardial fibers and loss of nuclei (Figure 2). No 

 inflammation was evident. Isopods were present 

 in the lumen of the ventricle. Isopod mouthparts 



Table l. — Population composition of Cirolana borealis present in five Carcharhinus milherti samples 



(see text) collected off the Florida Atlantic coast in 1978. 



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