Venomous snakes live in a different cognitive world than we do. “Mammals have already reached their peak before they can sense an animal and start moving,” said zoologist Alistair Evans of Monash University in Australia.
Because in competitions of reflexes, snakes usually win. It takes mice and humans less than half a second to recognize and react to a threat. However, a venomous snake can swoop down and bite its prey in that fraction of a second.
It was hard to even visualize this process because it happened so fast. Evans and his colleagues decided to use high-speed video cameras to record and reconstruct the rapid and complex movements of 36 species of venomous snakes.
The results, described in a study published last month in the Journal of Experimental Biology, offer a glimpse into the different approaches these creatures take to penetrate their victims with their fangs.
To conduct the experiment, Evans needed a snake. So he turned to biologist Anthony Herrell of the National Museum of Natural History in Paris, who collaborates on research with Venomworld, a French company that produces the venom used to make antivenom.
Herrell, along with the Venomworld team and Silke Kreulen, then a graduate student at Monash University, photographed the snake at 1,000 frames per second. Operating under strict security protocols, they attached a cylinder of ballistic gel (heated to mimic mammalian body temperature) to the end of a long pole. Then they introduced him to three families of snakes.
Animals often make mistakes. However, when his attacks were successful, the results were impressive.
Vipers, one of the groups studied, are ambush predators. They curl up in one place, retract and wait for large prey. It bursts into action when prey approaches, smoothly and quickly increasing its head speed.
In one video featuring a venomous snake, Herrell said, within tens of milliseconds, “the snake opens its mouth and, “wham,” and the fangs are inserted.” After injecting the venom, the snake released the cylinder.
In nature, this bite-and-release technique allows the snake to administer venom and retreat if the victim fights back. Even if the prey escapes, it will eventually die from the poison. Then, using its tongue to trace the footprints of the destined animal, the snake can eat in peace.
The researchers also observed how the pit vipers adjusted their bites after contact. They removed one prey at a time, moving their teeth forward until they could penetrate better and deeper.
According to Herrel, this information can contribute to the design of protective gear. However, he stressed that most snakes are “not very dangerous” if left alone.
In one of the videos, a viper breaks its right fang after coming into contact with the gel, sending its teeth spiraling into the air. “It had never been captured on film before,” Evans said. (Don’t worry, snakes change prey regularly.)
The second snake family tested was Elphidae, a group that includes cobras, mambas, and taipans. The four species the researchers studied tended to approach their prey, attack more slowly than most pit vipers, and clench their jaws repeatedly. Each time the jaw muscles contract, venom is forced through the fangs and injected into the prey.
Finally, there are colubrids, only a few of which pose a toxic threat to humans. The researchers looked at two species that, unlike pit vipers and colapids, have fangs located at the back of their mouths. When the snake came into contact with the gel, it dragged its teeth over it and tore the would-be victim apart, allowing the venom released from its rear fangs to flow into the open wound.
“This is a great data set because animals are notorious for not doing what humans want them to do,” said Jessica L. Tingle, a biologist at Brown University who was not involved in the study. “This helps us understand how attacks work, in part because diversity is at the heart of much of biology.”
Tingle’s only criticism is that most of the snakes were vipers. “I think we need to be cautious about generalizing the results to groups like pythons and boas,” she says. The study looked at several colubrids, which make up half of all snake species.
Herrell found a variety of snake behaviors noteworthy. “We thought these attacks were very routine, like little robots doing the same thing all the time.”
Video he and his colleagues collected revealed the opposite. “These animals are much more flexible. They can do much more than most people think,” Herrell said.
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