Observations on Crayfish Predation by Water Snakes, 
Nerodia (Reptilia: Colubridae) 
Lance W. Fontenot and Steven G. Platt 
Department of Biological Sciences, Clemson University , 
Clemson, South Carolina 29634-1903 
AND 
Christine M. Dwyer 
Museum of Natural History and Department of Systematics and Ecology, 
The University of Kansas, Lawrence, Kansas 66044-2454 
ABSTRACT — Field observations of ingestion of crayfish are reported 
for the colubrid snake Nerodia cyclopion. We surmise that the 
presence of crayfish in the gut contents of water snakes might 
not be attributable solely to secondary ingestion of other food 
items. Crayfish seem to be of minor importance in the diet of 
water snakes, but patterns of use of this food resource are still 
poorly understood. Future studies should indicate the size and de- 
gree of digestion of crayfish so that a determination of primary 
or secondary ingestion can be made. 
Water snakes of the genus Nerodia generally prey on fish and 
frogs (Mushinsky 1987), unlike the closely related crayfish special- 
ists in the genus Regina. However, the importance of other prey 
items is unclear. The significance of crayfish in the diets of fishes, 
amphibians, and reptiles has been addressed by Penn (1950) and 
Neill (1951). Penn (1950) noted that crayfish were important in the 
diet of Nerodia erythrogaster, but this conclusion was based on 
examination of only one specimen. Based on observations of re- 
cently captured N. sipedon disgorging crayfishes, Neill (1951) re- 
ported that N. rhombifer and N. sipedon also included crayfish in 
their diets. 
Most of the literature concerning the predation of crayfish by 
water snakes is based on examination of stomach contents and not 
on field observations of actual ingestion. Neill and Allen (1956) 
argued that care must be taken in analyzing feeding habits of snakes 
so as not to discount the possibility of secondary ingestion (obtain- 
ing prey items from the gut of the primary prey species) of food 
items. They suggested that crayfish fragments found in the stom- 
achs of N. erythrogaster and N. sipedon might represent the stom- 
ach contents of fishes ingested by snakes. The chitinous exoskeleton 
of crayfish might be more resistant to digestion than the tissues of 
primary vertebrate prey, and therefore, the exoskeleton will persist 
Brimleyana 19:95-99, December 1993 
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