Figure l. — Heart of a mature sandbar shark, Carcharhinus milherti, taken off the Florida Atlantic coast in 1978. Note Cirolana 



horealis enpocketed in the tissues of the ventricle. 



were attached to the myocardium and on the 

 endocardial surface of the ventricle; one area of 

 the ventricle showed signs of endocardial and 

 myocardial degeneration. The ventricular valves 

 appeared morphologically normal (thus, the iso- 

 pod in the conus in this sample had not entered 

 from the ventricle). Isopod mouthparts were also 

 attached on the pericardial surface, and there 

 were foci of mononuclear cell infiltrate in the 

 pericardium, indicating mild inflammation. 



There was remarkedly little inflammation in 

 the heart sample, but it is well documented that 

 sharks demonstrate a surprising lack of inflam- 

 matory response to trauma (Sigel et al. 1968; Bird 

 1978). The pathologist^ dated the time of necrosis 

 development in the shark heart muscle as 18-24 h 

 before death, because of the lack of inflammatory 

 cells (as would be true in a human heart). He 



stated the lesion should be older, however, because 

 of the loss of nuclei from the affected muscle cells. 



Discussion 



The occurrence of C. borealis in nearshore 

 Atlantic waters and in the hearts of sharks ap- 

 peared to be an unusual phenomenon. This is 

 indicated by the absence of the species in historic 

 records of faunal surveys and fishery operations in 

 the area. The large shark fishery at Salerno, Fla., 

 operated from 1935 to 1950 with no observed 

 depredation of catch by C. borealis (Springer^). 

 The occurrence in 1977 and 1978 might have 

 passed unnoticed, however, had it not been for 

 its effect on the Cape Canaveral fishery and 

 the serendipitous opening of the heart cavity 

 of a shark. It is probable that the isopods were 



'William H. Luer, Department of Pathology, Tulane Univer- 

 sity, School of Medicine, 1430 Tulane Avenue, New Orleans, 

 LA 70112, pers. commun. April 1980. 



''Stewart Springer, Senior Research Associate, Mote Marine 

 Laboratory, 1600 City Island Park, Sarasota, FL 33577, pers. 

 commun. October 1978. 



380 



