Burmese pythons are voracious eaters, devouring almost anything that crosses their paths—even quite a few white-tailed deer and other large mammals. So is there a limit to how far these slippery carnivores can stretch their jaws to sweep up large prey? Maybe not, scientists recently learned.
These pythons are huge compared to other snakes, reaching about 18 feet (5.5 meters) in length and weigh up to 200 pounds (91 kg). However, a study was published on August 25 in the journal Integrated Organismal Biology (opens in new tab) found that their girth is not what determines why hungry pythons can gobble up large meals. Instead, the secret lies in the snakes’ gap – how wide they can open their mouths.
Biologists from the University of Cincinnati wanted to test how euthanized Burmese pythons (Python bivittatus) could stretch their jaws for a snack. It is widely believed – and wrongly – that snakes can dislocate or detach their jaws to swallow prey. In fact, a stretchy piece of connective tissue extends from the snake’s braincase, or skull, to its lower jaw, allowing the animal to swallow the massive spine.
“The key thing about snakes is that they don’t dislocate their joints at all in the process of swallowing their prey,” Bruce Jayne, the study’s lead author and a biologist and professor at the University of Cincinnati, told Live Science. “But the joints they have between their bones are extremely mobile [human] the jaws, which are one piece, in snakes, are two pieces. And between these two pieces are connective tissues, skin and muscles”.
Related: Largest python ever found in Florida measures 18 feet long and weighs 200 pounds
All these pieces fit together to form a highly mobile mechanism that allows non-venomous pythons to open their mouths wide and swallow their prey. Once an animal catches the snake, the bollard predator wraps its long body around the victim to cut off its blood flow before devouring it – whether the victim is dead or still breathing.
Using a series of 3D-printed plastic probes in various sizes, the scientists tested different individual pythons with probes of increasing sizes, measuring the maximum amount each animal could open its mouth. The largest probe was 9 inches (22 cm) in diameter and looked strikingly like an orange Home Depot bin. Only one snake was able to stretch its gape wide enough to accommodate the giant probe: a python that weighs about 59 kilograms and is 14 feet (4.3 meters) long.
“The catheter is big enough to fit over my head,” Jayne said. “To give you an idea of how big this sample was, it’s too big to fit inside a 5 gallon [20 liters] bin. That was heavy.”
Burmese pythons are abundant in the Florida Everglades, but they are an invasive species that is decimating local animal populations. For the study, biologists worked with area hunters to gain access to euthanasia specimens that had been killed to help reduce the invasive population. This limited the size of snakes that Jayne and his team could test in their experiments.
“I wish I could get bigger pythons because one thing people always want to know is what the biggest gap is,” Jayne said. “I think some could have a gap diameter as large as 30 inches [76 cm].”
The study also found that precisely because snakes have adaptable jaws, not all snake species can open their mouths as wide as a Burmese python. When biologists tested the snakes of brown snakes (Boiga irregularis) — another invasive species that feeds on birds, lizards and small rodents — found that brown tree snakes, which are about the same length as Burmese pythons but much less bulky, couldn’t look at their faces as much as their older Burmese cousins could.
“The size between the two species was amazing,” Jayne said. “If you compare gap to mass, the two species would be similar. But pythons, even after correcting for that fact, are much heavier snakes and still have larger gaps.”
However, Jayne cautioned that just because pythons can open their mouths wide, it doesn’t mean all of their meals consist of large mammals. In fact, a large part of their diet includes smaller prey, such as e.g bunniesfoxes and raccoons.
“The anatomy of snakes puts an upper limit on what they can eat, since they don’t take bites out of their prey, they swallow it whole,” he said. “Just because they have this anatomical ability doesn’t mean they use it regularly. Very often the prey can be difficult to capture and swallow. I’m very interested to watch and see what their anatomy allows.”