The discovery by Jayne, Harold Voris of the Field Museum of Natural History, and Peter Ng of the National University of Singapore, is reported in the July 11 issue of Nature.
"The snake literally rips the crab's body apart," said Jayne. "They'll tug and pull on it to tear it apart."
The researchers were trying to understand the diets of two snakes found in Singapore Fordonia leucobalia and Gerarda prevostiana. Both eat crabs, which is fairly unusual right from the start. However, while examining the stomach contents, it was obvious that crabs eaten by Gerarda were in pieces. Since crabs can drop (autotomize) their limbs and joints can break as a crab is captured and eaten, it was important to verify how the crab is actually pulled apart.
So, Jayne brought the snake into his laboratory and recorded Gerarda's feeding behavior using an infrared IR) camera. "They're kind of a bashful species," said Jayne. They wouldn't eat when I watched them, but when I used the IR camera I found out there was this stereotypical behavior."
The snake forms itself into a loop and uses the loop to hold and tear apart its prey. The ability to rip the crabs apart was a surprise, because snake teeth are not adapted for slicing and cutting. Instead, they curve back into the mouth which is an adaptation for holding the prey inside the mouth.
Fordonia, on the other hand, has no stereotypical behavior for pulling its crab prey apart, although they do occasionally break the legs off hard-shelled crabs. "When fed soft-shell crabs, they make a mess of it," said Jayne. That limits the size of prey Fordonia can eat while Gerarda
Contact: Chris Curran
University of Cincinnati