Size alone doesn’t explain how invasive Burmese pythons eat such large prey

Burmese pythons are not only large snakes, reaching over 18 feet and 200 pounds, but big eaters, taking prey as large as a deer.

University of Cincinnati biologists have discovered that it’s not just the size of its head and body that puts almost everything on a python’s menu. They have evolved super stretchy skin between their lower jaws, which allows them to consume prey up to six times larger than similarly sized snakes.

The study, funded in part by a grant from the National Science Foundation, was published in the journal Integrative Organic Biology.

Since most snakes swallow their prey whole, they must have a wide mouth to accommodate a meal. Unlike our lower jaw, the lower jaws of snakes are not connected, allowing them to open wide.

“The stretchy skin between the left and right lower jaws is dramatically different in pythons. Just over 40% of their total open area comes on average from stretchable skin,” said lead author and professor Bruce Jayne. of biology at UC. “Even after correcting their big heads, their openness is huge.”

Pythons are constrictors. They bite their prey and envelop it in their powerful rings, fatally cutting off the animal’s vital blood flow, before consuming it whole at will.

The larger the prey, the more energy a snake gets from a meal. For pythons, that means not having to hunt as often, which can come with considerable risk in a world full of busy roads and dangerous predators.

In addition to pythons, Jayne has studied the aperture size of brown tree snakes, a mildly venomous tree specialist that hunts birds and other animals in the forest canopy. Brown tree snakes were introduced in the 1950s to Guam, wiping out many bird species.

In addition to measuring snakes, Jayne also measured the dimensions and weights of potential prey. This allowed Jayne to use the size of the snake to predict the maximum size of its prey and the relative advantages of consuming different types such as alligators, chickens, rats or deer.

Small snakes derive greater relative prey mass benefits from a modest increase in aperture size, the study found. This gives baby pythons an early advantage in taking on a wider range of prey than other snakes their size, Jayne said.

Being big also helps snakes avoid becoming meals themselves. Snakes are preyed upon by everything from waders to minks and raccoons to alligators and other snakes.

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

Like the invasive brown tree snakes in Guam, Burmese pythons wreak havoc on the ecology of Everglades National Park where they were introduced due to the release of captive animals from the exotic pet trade in the 1980s.

Study co-author Ian Bartoszek works as an environmental science project manager for the Conservancy of Southwest Florida, where he led a python monitoring project. They implant radio transmitters into the male snakes during the breeding season to find the females before they can lay any more eggs. A large female python can lay more than 100 eggs.

Researchers regularly find deer hooves and the remains of other large animals in their stomachs. Bartoszek photographed a python regurgitating an adult white-tailed deer.

“The Everglades ecosystem is changing in real time based on one species, the Burmese python,” Bartoszek said.

The good news is that pythons rarely attack people. Bartoszek said the only defensive encounters he had with wild pythons were with females guarding their nests.

“It’s much more dangerous to drive there than to work with the snakes,” he said.

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Material provided by University of Cincinnati. Original written by Michael Miller. Note: Content may be edited for style and length.

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