For Immediate Release The Field Museum, Greg Borzo (312) 665-7106 gborzo@fieldmuseum.org Unique feeding behavior discovered for snakes Field Museum scientists describe “loop and pull” in Nature The top 2 infrared images show the snake, Gerarda prevostiana, eating a crab by the "loop and pull" method. The bottom image shows five pieces of crab that could be swallowed by this snake -- once they are pulled off the crab. The full crab shown is the approximate size of the crab this snake ate by "loop and pull." Finally, the 13-mm diameter circle is the maximum gape of the snake, i.e., the maximum size of the mouth opening. CHICAGO – Snakes are known to swallow their prey whole, which limits the size of what they can eat. But now scientists have discovered that a species of snake can tear apart its prey. This snake loops its body around a crab to hold one end while using its mouth to pull off legs or rip the crab’s body into pieces. This “loop and pull” method allows a snake to eat crabs that are relatively huge – far too large to swallow whole. Even more astounding, this appears to be solely based on a unique behavior rather than newly derived physical traits. The research will be published in Nature July 11, 2002. “This rather ordinary looking snake is breaking all the rules,” says Harold Voris, co-author and curator of amphibians and reptiles at The Field Museum. “Gerarda prevostiana is the only snake to tear oversized prey apart, yet you could not have predicted this on the basis of its morphology [form and structure]. It appears to have accomplished this feat solely through a unique behavior, not morphological adaptation.” In fact, the novel behavior has overcome the limitations that limb loss and body form changes imposed on snakes early in their evolution, Voris says. “These results serve notice that behavioral changes alone may allow for major and exceptional changes in life style.” The snakes and crabs were collected in a mangrove forest of Singapore. The unique feeding behavior was recorded at night in a dark room with infrared video cameras. In 85% of the trials, the snake used “loop and pull.” The scientists captured two G. prevostiana that had consumed pieces of crabs much larger than any used in the lab trials. This verified that the feeding behavior was not limited to the lab. Continue