From rabbits and rats to crocodiles and deer, how can Burmese pythons swallow almost anything?

In a new study, researchers take a closer look at the biology of the huge Burmese python, which can reach up to 5 meters in length, and specifically their ability to devour any creature they come across.

Burmese pythons are not just large snakes, but are voracious eaters, consuming a meal in the form of large prey such as crocodiles or deer.

But their sheer size alone cannot explain the amazing yawning required to swallow deer-sized prey.

A snake yawns is how much or how far an animal can open its mouth, and since snakes tend to swallow their prey whole, without chewing it first, yawning is a major factor in determining what it can eat.

And the study - published in the journal Integrative Organismal Biology and covered in a University of Cincinnati press release on September 16 - found that Burmese snakes have a special advantage to open their already large mouths more widely. Namely: the highly stretched skin between its lower jaws allowing it to grip larger animals than its highly mobile jaws alone would allow.

Researchers have taken a closer look at the biology of Burmese pythons and their ability to devour any creature they come across (University of Cincinnati)

A wider range of prey

Since most snakes swallow their prey whole, they must have wide mouths to accommodate the meal, so the bones of the lower jaws of snakes are not connected, allowing them to open wide.

While the stretchy jaws may be a criterion for a snake's ability to devour prey, the highly stretchy skin of the Burmese pythons' lower jaws is transitioning to a new high level of flexibility.

The research team found that the skin of the Burmese python is very stretchy between its lower jaws, which allows it to eat larger animals than the jaws of an ordinary python allow, and allows it to consume prey 6 times larger than snakes of similar size.

"The elastic skin between the right and left mandibles is radically different in snakes...more than 40% of their total yawning area is, on average, stretchy skin," study co-author Bruce Jayne, an evolutionary biologist at the University of Cincinnati, explains in a university news release. .

Measuring snakes' mouths enables researchers to estimate the largest animals they can eat (University of Cincinnati)

lasso movement

In his lab, Jain studies the limitations of animal anatomy and how this affects their behaviour.

And in 2020, he identified an unprecedented, documented method of snake movement he called the 'lasso' movement, in which some snakes climb wide cylinders or smooth tree trunks.

Jain and colleagues also examined the mouths of brown tree snakes, as these small, venomous snakes hunt birds and other small prey from other animals.

By measuring snakes' mouths as well as their potential prey, researchers can estimate the largest animals snakes can eat, along with the relative benefits of eating different prey options, ranging from rats and rabbits to crocodiles and deer.

The data suggests that smaller snakes can benefit more from the enlarged yawn volume, which enables them to eat relatively larger prey.

Jain also measured the dimensions and weights of potential prey animals, and this allowed him to use the size of a snake to predict the maximum size of its prey and the relative benefits of consuming different types of food such as crocodiles, chickens, rats or deer.

Burmese pythons in the US state of Florida are an invasive species, eliminating native species (University of Cincinnati)

Understanding Biological Curiosity

Burmese pythons in the US state of Florida are invasive, wiping out native species and destroying the ecosystem by eating almost everything available.

Burmese pythons wreaked havoc on the environment in Everglades National Park, where they were introduced through the accidental or deliberate release of captive animals into the exotic pet trade in the 1980s.

By knowing the upper limits of the prey that invasive snakes can eat, biologists hope to understand how they affect the food chain.

The new research is more about understanding biological curiosity than knowing how to control invasive species, but it could at least help scientists predict the ripple effects of Burmese pythons on wetland ecosystems.

"It won't help control them, but it can help us understand the impact of invasive species," says Jain. "If you know how big snakes are and how long it takes to get to that size, you can put an approximate upper limit on the resources a snake is expected to exploit."