Paper Electrophoresis Patterns of Sera from Seven Genera of 
Decapod Crustaceans 
Lawrence D. Hughes 1 and Lindsay R. Winkler 2 
ABSTRACT: The pattern noted for the various families was simple, showing one 
major protein band and, in most cases, at least one minor one. Serum from crabs 
from the open coast always showed two bands, while those from the mud flats 
showed but one. This held even in Pachygrapsus, which is found in both habitats. 
Recently Woods et al. (1958) reported a very 
close similarity in the electrophoretic patterns 
in starch gel of related species of crabs, and 
stated that, not without exceptions, such elec- 
trophoretic relationships seemed to extend to 
the family level. This work prompted the 
authors to do a cursory study of representatives 
of a number of the families of crabs common 
to the southern California coast. 
Paper electrophoresis rather than starch gel 
was used, employing the Spinco Model R 
electrophoresis apparatus to separate the serum 
proteins of specimens from eight genera of 
decapod crustaceans, representing seven fami- 
lies. The separations were made on individual 
samples, and, in the case of the smaller species, 
on pooled samples in a veronal buffer at pH 8.6 
with an ionic strength of .075. The liquid sera 
were separated from the clot and applied to the 
paper strips and run at 5 milliamperes for 16 
hr. Since only the Grapsidae were represented 
by more than one genus, no generalization can 
be made as to uniformity within the families. 
Differences noted among the families in- 
cluded (a) rapidity of migration of the major 
band, (b) relative migration of the minor band, 
(c) strength of the two bands both relative 
and absolute, and (d) the appearance of a third 
band in the case of the Pleuroncodes (Gala- 
theidae) (Fig. 1, £.). This latter may be of 
significance in view of the uncertain taxonomic 
position of the Galatheidae, and, if it is found 
to be a consistent characteristic in large numbers 
1 Present address: Box 578, Dunnellon, Florida. 
2 Formerly at Department of Pharmacology, School 
of Medicine, Loma Linda University, Loma Linda, 
California. Present address: College of the Desert, 
Palm Desert, California. Manuscript received Sep- 
tember 13, 1965. 
of specimens, might easily be construed to sup- 
port a more distant relationship with the main 
body of the crabs. 
However, there appears to be an environ- 
mental as well as a genetic relationship in the 
electrophoretic patterns of the serum proteins 
of these animals. It will be noted from Figure 
1 that those forms which are more commonly 
associated environmentally tend to have a broad 
similarity in their electrophoretic patterns. This 
environmental pattern is shown to exist even 
within the species in the case of Pachygrapsus 
crassipes Randall which, in Southern California, 
lives on the margins of the mud flats as well as 
in the rocky intertidal zone of the open coast. 
All the crabs living in the open water (Fig. 
1, A-E) and on the well aerated tidal zones, 
including P. crassipes (Grapsidae), show two 
well-defined protein components, whereas all 
those (again including P. crassipes ) taken from 
the muddy shores (Fig. 1 , F-H), where 
routinely there are wide variations in the tides 
and high salinity— low oxygen relationships, 
have but one protein component. 
The food supply available to these two en- 
vironmental groups of crabs also differs widely. 
The former group has abundant supplies of 
red, brown, and green algae, as well as various 
forms of animal life. The second group, living 
on the mud flats, has a much more limited food 
supply, consisting of small green algae and 
saline higher plants, supplemented by more 
limited amounts of animal and plant material. 
In addition, the population levels of P. crassipes 
on the beaches studied were much lower than 
they were on the muddy shores, which may 
have been a significant influence in the latter 
group. 
The almost identical patterns of Hemigrap- 
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