Pythons can swallow almost anything. A new study shows how: ScienceAlert

Burmese pythons are huge, reaching up to 5 meters (16 ft) in length. But their enormous size alone cannot explain their incredible gaping hole—the amount the animal can open its mouth—required to swallow prey as large as deer or alligators.

A new study details how Burmese pythons (Python molorus bivittatus) have developed a unique feature that allows their jaws to stretch enough to swallow prey up to six times larger than some similarly sized snakes can eat.

Despite their voracious appetites, wild Burmese pythons are actually vulnerable in their native Southeast Asia, in part due to human-induced habitat loss.

But in Florida, where they have been introduced, they are decimating native species and damaging the ecosystem by eating almost everything in sight.

Burmese python snares an adult white-tailed deer in Everglades National Park. (Ian Bartozek)

“The Everglades ecosystem is changing in real time based on one species, the Burmese python,” says Ian Bartoszek, environmental scientist for the Conservancy of Southwest Florida.

In the new study, Bartoszek and three other researchers took a closer look at the biology of this massive snake, specifically its ability to eat almost any creature it encounters.

To help their already large mouths open even wider, the study found that Burmese pythons evolved a special feature: extremely stretchy skin between their lower jaws that allows them to devour animals even larger than their teeth alone would allow. their very mobile jaws.

Because snakes tend to swallow their prey whole, without chewing it first, their gap is a key factor in determining what they can eat.

Snake skull scan
CT scan of Burmese python jaws. (Jayne et al., Integrated Organismal Biology2022)

Unlike the mandibles of humans and other mammals, the mandibles of snakes are not fused, but are loosely connected by an elastic ligament, allowing their mouths to open wider.

But while expandable jaws may be typical of snakes, the highly stretched skin on the lower jaws of Burmese pythons takes it to a new level of elasticity, explains study co-author and University of Cincinnati evolutionary biologist Bruce Jayne.

“The elastic skin between the left and right mandibles is radically different in pythons. Just over 40 percent of their total surface area on average is elastic skin,” says Jayne.

“Even after you fix their big heads, their gap is huge.”

To see how the snakes’ gap compared to their body size, Jayne and his colleagues also examined the gap of wild and captive brown tree snakes (Boiga irregularis) along with that of Burmese pythons.

These smaller snakes, which are mildly venomous, hunt birds and other small game in the forest canopy.

python and brown snake with open mouth
The gap between a Burmese python (left) and a brown tree snake (inset). (Bruce Jane)

By measuring the snakes as well as their potential prey, the researchers were able to estimate the largest animals the snakes could eat, along with the relative benefits of eating different prey options, from rats and rabbits to alligators and white-tailed deer.

The data suggest that smaller snakes have more to gain from an expanded size that allows them to eat relatively larger prey. This means that baby pythons have a leg up (figuratively) on other snakes their size, as they can exploit a wider range of prey.

Larger body size not only provides a wider menu for snakes, the researchers add, but also helps them stay off the menu for other predators.

“When these pythons get to a reasonable size, it’s pretty much only alligators that can eat them,” says Jayne. “And pythons eat alligators.”

Previous research shows that clamps like Burmese pythons kill their prey not by suffocation, but by cutting off the helpless animals’ blood flow.

While the new research is more about understanding a biological curiosity than figuring out how to control an invasive species, it could at least help scientists predict the cascading effects of Burmese pythons on wetland ecosystems.

“It’s not going to help them control them,” says Jayne. “But it can help us understand the impact of invasive species. If you know how big snakes get and how long it takes them to get that size, you can put a rough upper limit on the resources the snake is expected to exploit.”

The study was published in Integrated Organismal Biology.

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