Pythons are true choke artists
Size alone doesn't explain how invasive Burmese pythons eat such big prey
Peer-Reviewed PublicationIMAGE: ECOLOGISTS WITH THE CONSERVANCY OF SOUTHWEST FLORIDA CAPTURE A 215-POUND BURMESE PYTHON IN EVERGLADES NATIONAL PARK. view more
CREDIT: IAN BARTOSZEK/CONSERVANCY OF SOUTHWEST FLORIDA
Burmese pythons are not just big snakes, growing to more than 18 feet and 200 pounds, but big eaters, taking on prey as large as a deer.
Biologists at the University of Cincinnati found that it’s not just the size of its head and body that puts almost everything on a python’s menu. They evolved super-stretchy skin between their lower jaws that allows them to consume prey up to six times larger than similar-sized snakes.
The study, funded in part by a grant from the National Science Foundation, was published in the journal Integrative Organismal Biology.
Since most snakes swallow prey whole, they must have wide mouths to accommodate a meal. Unlike our lower jawbone, the lower jawbones of snakes are not connected, allowing them to open wide.
“The stretchy skin between left and right lower jaws is radically different in pythons. Just over 40% of their total gape area on average is from stretchy skin,” lead author and UC biology professor Bruce Jayne said. “Even after you correct for their large heads, their gape is enormous.”
Pythons are constrictors. They bite their prey and wrap their powerful coils around it, fatally cutting off the animal’s vital blood flow, before consuming it whole at their leisure.
The bigger the prey, the more energy a snake derives from a meal. For pythons, that means not having to hunt as often, which can carry extensive risk in a world full of busy roads and dangerous predators.
Along with pythons, Jayne studied the gape size of brown tree snakes, a mildly venomous arboreal 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.
Besides measuring the snakes, Jayne also measured the dimensions and weight of potential prey animals. This allowed Jayne to use snake size to predict the maximal size of its prey and the relative benefits of consuming different types such as alligators, chickens, rats or deer.
Small snakes derive greater benefits in relative prey mass from a modest increase in gape size, the study found. This gives python babies an early advantage in taking on a broader range of prey compared to other snakes their size, Jayne said.
Being big also helps snakes avoid becoming meals themselves. Snakes fall prey to everything from wading birds to minks and raccoons to alligators and other snakes.
“Once those pythons get to a reasonable size, it’s pretty much just alligators that can eat them,” Jayne said. “And pythons eat alligators.”
Like invasive brown tree snakes in Guam, Burmese pythons are wreaking 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 has led a project to track pythons. They implant radio transmitters in male snakes during breeding season to find females before they can lay more clutches of eggs. A big female python can lay more than 100 eggs.
Researchers routinely find deer hooves and the remains of other big animals in their stomachs. Bartoszek photographed one python regurgitating a full-grown 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’s had with wild pythons are with females guarding their nests.
“It’s way more dangerous to drive there than to work with the snakes,” he said.
CAPTION
University of Cincinnati professor Bruce Jayne demonstrates the gape of a euthanized Burmese python specimen in his lab.
CREDIT
Bruce Jayne
CAPTION
A Burmese python in Everglades National Park regurgitates a white-tailed deer.
CREDIT
Ian Bartoszek/Conservancy of Southwest Florida
CAPTION
University of Cincinnati professor Bruce Jayne works with a brown tree snake in his biology lab.
CREDIT
Joseph Fuqua II/UC
JOURNAL
Integrative Organismal Biology
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Scaling Relationships of Maximal Gape in Two Species of Large Invasive Snakes, Brown Treesnakes and Burmese Pythons, and Implications for Maximal Prey Size
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