Ever since Herman Schlegel denied the fact that rear-fanged snakes were venomous in the early 19th century, science has been resisting the idea. Many snakes have fangs located on the rear of the maxillary bone, and many of those fangs have open grooves, the gooves are often connected to a venom gland. These snakes bite and hold their prey, chewing to work the venom into the animal so that it can be subdued before being swallowed. Previous studies have suggested the venom in snakes with fangs on the front of the maxillary bone (vipers, elapids, and Atracapsis) inject their venom under under high pressure, while those with open gooves in their fangs have venom that is moving under low pressure.
The open grooved, rear fang of the Masked Water
Snake, Homalopsis buccata (left), and the closed
front fang of the Death Adder, Acanthophis
antarticus (right). JCM
Bruce Young from the University of Massachusetts at Lowell and the Technische Universität München (the Technical University of Munich, Germany) now provide an explanation how snakes use grooved fangs to deposit venom in prey. Snake venom is viscous and a non-Newtonian fluid,behaving sometimes like a solid and at other times like a liquid. Other non-Newtonian fluids include things like ketchup and Silly Putty.
Snake venom is rich in proteins, macromolecules that caus it to have a high viscosity and flow about 500 times more slowly than water. Despite this it flows fast enough down a fang and into a victim at about one centimeter per second (water flows about 7,000 centimeters a second). Snake venom changes its viscosity. When flowing througjh a fang, the venom has a high viscosity, clinging to the fang as the snake prepares to bite. When a snake sinks its fangs into a victim, the three walls of the grooved fang are sealed by the prey's tissue and forming a hollow venom tube (just like thant found in front-fanged snakes) allowing the venom to reach the deeper tissue layers where it will be picked up by the blood and distributed around the prey's body.
Labels: rear-fanged snakes, venom flow