NOTES 



ELECTROPHORETIC ANALYSES OF 



HEMOCYANINS FROM FOUR SPECIES OF 



MUD CRABS, GENUS PANOPEUS, WITH 



OBSERVATIONS ON THE ECOLOGY 



OFF. OBESUS 



analyses were made by inj ecting 1 ml of Formalin 1 in- 

 to the cardiac region of the crab at the time of collec- 

 tion, and later, following its removal, contents of the 

 cardiac stomach were examined under a binocular 

 dissecting microscope. 



The mud crab, known until now as Panopeus herbstii 

 H. Milne Edwards, s.L, of the family Xanthidae, has 

 been regarded as a common intertidal species 

 throughout much of its range in the western Atlantic. 

 As such, it commonly has been used in ecological, 

 physiological, and genetic studies (reviewed in 

 McDonald 1977). Four morphological forms (Rath- 

 bun 1930) are recognized as species in the paper by 

 Williams (1983), their ranges outlined, and habitat 

 preferences shown. 



As part of the study on the genetic control of 

 hemocyanin production, we examined several hun- 

 dred individuals from coastal North Carolina and 

 found considerable evidence that two of these four 

 forms represent separate gene pools. Additional field 

 observations revealed that these two forms occupy 

 distinct areas in the intertidal zone, exhibit be- 

 havioral differences, and consume different prey. 

 However, morphological differences other than color 

 appeared to be slight. Smaller collections of Pan- 

 opeus were made at Charleston, S.C., Big Pine Key 

 and St. Petersburg, Fla., and Grand Terre Island, La. 

 These included individuals representing the species 

 P. herbstii H. Milne Edwards, s.s., P. lacustris Des- 

 bonne, P. obesus Smith, and P. simpsoni Rathbun. 

 Electrophoretic analyses of their hemocyanins pro- 

 vide data that are compatible with taxonomic treat- 

 ment of each as a distinct gene pool. 



Materials and Methods 



Crabs were collected by hand at low tide from the in- 

 tertidal zone. Although ecological studies were con- 

 fined to the area around Pivers Island, Beaufort, 

 N.C., additional material was collected at Harkers 

 Island and Swansboro, N.C., and at the localities 

 mentioned above. Crabs from Big Pine Key and 

 Grand Terre Island were shipped by air to Beaufort. 

 The remaining crabs were bled at the collecting sites 

 and hemocyanin samples transported on ice to 

 Beaufort. Electrophoretic analysis of hemocyanins 

 was performed following dissociation to monomeric 

 subunits according to the methods of Sullivan et al. 

 (1974) and Sullivan and Tentori (1981). Stomach 



Results 



In studying the electrophoretic patterns of hemo- 

 cyanin from the forms of P. herbstii, s.L (Fig. 1), we 

 associated an aberrent pattern with the color morph 

 now recognized as P. obesus (Williams 1983). Con- 

 ditions of preparation and electrophoresis of hemo- 

 cyanins cause the polymeric hemocyanin to dis- 

 sociate into subunits (Sullivan et al. 1974). The 

 patterns shown in Figure 1 represent monomeric 

 hemocyanin subunits. Six loci are active in a fiddler 

 crab, Uea pugilator (Bosc), but the polypeptides of- 



1 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



ORIGIN -► 



B 



FIGURE 1.— Electrophoretic patterns of monomeric hemocyanins 

 from Panopeus herbstii, s.s. (A), P. obesus (B), P. lacustris (C), P. 

 simpsoni (D), and Uca pugilator (E) for comparison. Only one of 

 several phenotypic patterns is shown. 



FISHERY BULLETIN: VOL. 81, NO. 4. 1983. 



883 



