Burmese pythons ( Python molorus bivittatus ) are not exactly small and can grow up to 5 meters long . However, its size alone does not explain its ability to open its mouth to unsuspected limits. It is capable of swallowing deer and alligators , prey up to six times larger than that ingested by similarly sized snakes.
The study has been published in Integrative Organismal Biology and in it the scientists conclude that the Burmese python has developed a unique feature that allows it to open its mouth wide and that is super-elastic skin between the lower jaws . The jaws of these pythons are already highly mobile, but with this advantage, the opening capacity is multiplied.
Snakes often swallow prey whole , without chewing it first. Whether they can open their mouth more or less will determine what they can or cannot eat. Unlike the lower jaws of humans and other mammals, the lower jaw bones of snakes are not fused together , but instead are loosely connected with an elastic ligament, allowing their mouths to open wider. Thus, although having extendable jaws is common in snakes, having superelastic skin, as in Burmese pythons, is not so common.
“The elastic skin between the left and right lower jaws is radically different in pythons. Just over 40 percent of the total surface area of their mouth is elastic skin,” says study co-author Bruce Jayne, an evolutionary biologist at the University from Cincinnati. “Even after correcting their big heads, their opening is huge.”
The scientists turned to another reptile, the brown tree snake ( Boiga irregularis ), to compare the animal’s mouth to its body size. This type of snake is smaller, slightly venomous, and feeds on birds and other small prey in the treetops.
They measured the snakes as well as their potential prey. In this way, they estimated what would be the largest prey that they could ingest. They also estimated the benefits they could get from eating different prey options, from rats and rabbits to alligators and white-tailed deer.
What was seen was that the smaller snakes were better off the larger their mouths were , as this allowed them to eat larger prey. Consequently, baby pythons have an advantage over other snakes of similar size, as they can feed on a broader catalog of prey. A larger body size, in addition to providing a more varied menu, allows the snakes to stay out of the reach of other predators.
“Once those pythons get to a reasonable size, it’s pretty much only alligators that can eat them,” says Jayne. “And pythons eat alligators.”
Jayne talks about alligators because the Burmese python is native to Southeast Asia (there it is in a vulnerable state) an introduced species in Florida that is killing the species in the area and damaging the ecosystem because it eats practically everything it sees. “The Everglades ecosystem is changing in real time based on one species, the Burmese python,” says Ian Bartoszek, an environmental scientist with the Conservancy of Southwest Florida.
Previous research has shown that constrictor snakes, such as Burmese pythons, do not kill their prey by suffocating them but by cutting off blood flow.
This research tries to understand a specific biological curiosity, but it could help scientists anticipate the consequences for wetland ecosystems of introducing Burmese pythons.
“It’s not going to help control them,” says Jayne. “But it can help us understand the impact of invasive species. If you know the size of the snakes and how long it takes them to reach that size, you can set a rough upper limit on the resources the snake can be expected to exploit.”
Referencia: Jayne, B., Bamberger, A., Mader, D., Bartoszek, I. Scaling Relationships of Maximal Gape in Two Species of Large Invasive Snakes, Brown Treesnakes and Burmese Pythons, and Implications for Maximal Prey Size. Integrative Organismal Biology. 2022. DOI: https://doi.org/10.1093/iob/obac033